Difference between revisions of "C-and-C++/C2/Functions/English-timed"

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|Welcome to the spoken tutorial on '''Functions in C and C++'''

|Welcome to the spoken tutorial on '''Functions in C and C++'''

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|In this tutorial we will learn,   

|In this tutorial we will learn,   

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|What is a '''function'''

|What is a '''function'''

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|-

|Syntax of a '''function'''

|Syntax of a '''function'''

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|-

|Significance of '''return statement'''

|Significance of '''return statement'''

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|-

| We will do this through examples.  

| We will do this through examples.  

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|-

|We will also see some common errors and their solutions.  

|We will also see some common errors and their solutions.  

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|-

| To record this tutorial, I am using,  

| To record this tutorial, I am using,  

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|-

|'''Ubuntu Operating System''' version 11.10

|'''Ubuntu Operating System''' version 11.10

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|-

| '''gcc''' and '''g++ Compiler''' version 4.6.1 .

| '''gcc''' and '''g++ Compiler''' version 4.6.1 .

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|-

|Let us start with the introduction to '''functions'''

|Let us start with the introduction to '''functions'''

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|-

|A '''function'' is a self-contained program executing a specific task.  

|A '''function'' is a self-contained program executing a specific task.  

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|Every program consists of one or more '''functions.'''  

|Every program consists of one or more '''functions.'''  

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|Once executed, the control will be returned back from where it was accessed.  

|Once executed, the control will be returned back from where it was accessed.  

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|-

|Let us see the syntax for '''function. '''

|Let us see the syntax for '''function. '''

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|'''ret-type''' defines the type of data that the '''function returns. '''

|'''ret-type''' defines the type of data that the '''function returns. '''

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|-

|'''fun_name''' defines the name of the '''function. '''

|'''fun_name''' defines the name of the '''function. '''

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|'''parameters''' is the list of '''variable''' names and their types.  

|'''parameters''' is the list of '''variable''' names and their types.  

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|We can specify an '''empty parameter list'''.  

|We can specify an '''empty parameter list'''.  

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|This is called as '''functions without arguments. '''

|This is called as '''functions without arguments. '''

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|And this is called as '''functions with arguments. '''

|And this is called as '''functions with arguments. '''

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|-

|Let us see a program using '''void. '''

|Let us see a program using '''void. '''

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|I have already typed the program on the editor.  

|I have already typed the program on the editor.  

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|So I will open it.  

|So I will open it.  

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|Note that our filename is '''function. '''

|Note that our filename is '''function. '''

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|And I have saved the file with the extentsion .c

|And I have saved the file with the extentsion .c

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|Let me explain the code.  

|Let me explain the code.  

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|This is our '''header file. '''

|This is our '''header file. '''

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|Before using any '''function''', it must be defined.  

|Before using any '''function''', it must be defined.  

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|Here we have defined a '''function''' called '''add.'''  

|Here we have defined a '''function''' called '''add.'''  

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|Note that '''add function''' is without any '''arguments.'''  

|Note that '''add function''' is without any '''arguments.'''  

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|And the return type is '''void. '''

|And the return type is '''void. '''

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|There are two types of functions-  

|There are two types of functions-  

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| '''User-defined''' that is our '''add function''' and  

| '''User-defined''' that is our '''add function''' and  

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| '''Pre-defined''' that is '''printf''' and '''main function '''

| '''Pre-defined''' that is '''printf''' and '''main function '''

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| Here we have initialized '''a''' and '''b''' by assigning them values as 2 and 3  

| Here we have initialized '''a''' and '''b''' by assigning them values as 2 and 3  

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| Here we have declared a variable '''c. '''

| Here we have declared a variable '''c. '''

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|Then we add the values of a and b.  

|Then we add the values of a and b.  

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|The result is stored in c.  

|The result is stored in c.  

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|Then we print the result.  

|Then we print the result.  

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| This is our '''main function. '''

| This is our '''main function. '''

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|Here we call the '''add function. '''

|Here we call the '''add function. '''

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|The addition operation will be performed and the result will be printed.  

|The addition operation will be performed and the result will be printed.  

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|-

| Now click on '''Save.'''

| Now click on '''Save.'''

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|-

|Let us execute the program.

|Let us execute the program.

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|Please open the terminal window by pressing '''Ctrl,  Alt''' and '''T ''' keys simultaneously.

|Please open the terminal window by pressing '''Ctrl,  Alt''' and '''T ''' keys simultaneously.

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|To compile, type '''gcc  function dot c  hyphen o  fun'''

|To compile, type '''gcc  function dot c  hyphen o  fun'''

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|To execute, type '''./fun''' (dot slash fun)

|To execute, type '''./fun''' (dot slash fun)

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|We see the output is displayed as '''Sum of a and b is 5 '''

|We see the output is displayed as '''Sum of a and b is 5 '''

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|-

|Now come back to our program.  

|Now come back to our program.  

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|Functions contains special identifiers called as '''parameters''' or '''arguments.'''  

|Functions contains special identifiers called as '''parameters''' or '''arguments.'''  

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|-

|Let us see the same example with arguments.  

|Let us see the same example with arguments.  

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|-

|I will change a few things here.  

|I will change a few things here.  

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|Type '''int add(int a, int b) '''

|Type '''int add(int a, int b) '''

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|Here we have declared a '''function add. '''

|Here we have declared a '''function add. '''

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|'''int a''' and '''int b''' are the '''arguments''' of the '''function add.'''  

|'''int a''' and '''int b''' are the '''arguments''' of the '''function add.'''  

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|-

|Let us delete this.  

|Let us delete this.  

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|No need to initialize a and b here.  

|No need to initialize a and b here.  

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|Delete the '''printf '''statement.  

|Delete the '''printf '''statement.  

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|Type '''int main() '''

|Type '''int main() '''

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| Let us declare a variable '''sum''' here.  

| Let us declare a variable '''sum''' here.  

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|Type '''int sum; '''

|Type '''int sum; '''

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|Then type '''sum = add(5,4); '''

|Then type '''sum = add(5,4); '''

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|Here we call the '''add function.'''  

|Here we call the '''add function.'''  

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|Then we pass the parameters as 5 and 4.  

|Then we pass the parameters as 5 and 4.  

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|5 will be stored in '''a''' and 4 will be stored in ''' b. '''

|5 will be stored in '''a''' and 4 will be stored in ''' b. '''

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|The addition operation will be performed.  

|The addition operation will be performed.  

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|Let us now print the result.  

|Let us now print the result.  

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|Hence type here  

|Hence type here  

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|'''printf(“Sum is %d\n”,sum);'''

|'''printf(“Sum is %d\n”,sum);'''

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|Delete this, as we have already called the function above.  

|Delete this, as we have already called the function above.  

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|Type return 0;  

|Type return 0;  

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|A '''non-void function''' must use a '''return''' statement that returns a value.  

|A '''non-void function''' must use a '''return''' statement that returns a value.  

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|-

|Click on '''Save'''

|Click on '''Save'''

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|-

|Let us execute the program.  

|Let us execute the program.  

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|Come back to our terminal.  

|Come back to our terminal.  

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|Now compile the program as before.

|Now compile the program as before.

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|Let us execute.  

|Let us execute.  

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|The output is displayed as '''Sum is 9 '''

|The output is displayed as '''Sum is 9 '''

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|Now let us see how to execute the same program in C++.  

|Now let us see how to execute the same program in C++.  

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|-

|Come back to our program.

|Come back to our program.

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|-

|Let me change a few things here.  

|Let me change a few things here.  

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|First press '''Shift, Ctrl and S''' keys simultaneously.  

|First press '''Shift, Ctrl and S''' keys simultaneously.  

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|Now save the file with '''.cpp''' extension.  

|Now save the file with '''.cpp''' extension.  

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|Click on '''Save'''.  

|Click on '''Save'''.  

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|First we will change the header file as <iostream>  

|First we will change the header file as <iostream>  

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|We will include the '''using''' statement here.  

|We will include the '''using''' statement here.  

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|The '''function declaration''' is same in C++.  

|The '''function declaration''' is same in C++.  

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|So there is no need to change anything here.  

|So there is no need to change anything here.  

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|Now replace the '''printf''' statement with the  '''cout''' statement, as we use cout<< function to print a line in C++.

|Now replace the '''printf''' statement with the  '''cout''' statement, as we use cout<< function to print a line in C++.

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|We don't need the '''format specifier''' and '''\n''' here.  

|We don't need the '''format specifier''' and '''\n''' here.  

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|Delete the '''comma.'''  

|Delete the '''comma.'''  

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|Now, type two opening '''angle brackets'''

|Now, type two opening '''angle brackets'''

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|After sum , again type two opening '''angle brackets'''.  

|After sum , again type two opening '''angle brackets'''.  

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|-

|Within double quotes, type '''backslash n'''.  

|Within double quotes, type '''backslash n'''.  

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|Delete this closing bracket.  

|Delete this closing bracket.  

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|Now Click on '''Save. '''

|Now Click on '''Save. '''

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|-

|Let us compile the program.  

|Let us compile the program.  

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|Come back to our terminal.

|Come back to our terminal.

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|Type '''g++ function dot cpp hyphen o fun1 '''

|Type '''g++ function dot cpp hyphen o fun1 '''

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|Here we have fun1, this is because we don't want to overwrite the output file fun.  

|Here we have fun1, this is because we don't want to overwrite the output file fun.  

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|Press '''Enter. '''

|Press '''Enter. '''

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|Type '''./fun1 '''

|Type '''./fun1 '''

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|The output is displayed as: Sum is 9  

|The output is displayed as: Sum is 9  

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|-

|Now we will see the common errors which we can come across.  

|Now we will see the common errors which we can come across.  

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|-

|Suppose here, we type x in  place of 4.  

|Suppose here, we type x in  place of 4.  

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|I will retain the rest of the code as it is.  

|I will retain the rest of the code as it is.  

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|Click on '''Save.'''  

|Click on '''Save.'''  

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|-

|Let us compile the program.  

|Let us compile the program.  

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|-

|We see an error at line no. 10.  

|We see an error at line no. 10.  

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|'''x was not declared in this scope. '''

|'''x was not declared in this scope. '''

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|This is because '''x''' is a '''character''' variable.

|This is because '''x''' is a '''character''' variable.

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|It was not declared anywhere.  

|It was not declared anywhere.  

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|And our '''add''' function has '''integer''' variable as an '''argument'''.  

|And our '''add''' function has '''integer''' variable as an '''argument'''.  

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|So, there is a mismatch in '''return type''' and '''return value'''.  

|So, there is a mismatch in '''return type''' and '''return value'''.  

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|-

|Now come back to our program.  

|Now come back to our program.  

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|Let us fix the error.  

|Let us fix the error.  

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|Type 4 at line no. 10.  

|Type 4 at line no. 10.  

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|-

|Click on '''Save. '''

|Click on '''Save. '''

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|-

|Let us execute again.  

|Let us execute again.  

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|Let me clear the prompt.  

|Let me clear the prompt.  

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|Compile the program as before.  

|Compile the program as before.  

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|Yes! it is working.  

|Yes! it is working.  

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|Now we will see another common error which we can come across.

|Now we will see another common error which we can come across.

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|Suppose here we pass only one parameter.   

|Suppose here we pass only one parameter.   

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|Delete 4.  

|Delete 4.  

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|Click on '''Save'''

|Click on '''Save'''

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|-

|Switch to the terminal.

|Switch to the terminal.

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| Let us compile.  

| Let us compile.  

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|-

|We see an error at line no 10.  

|We see an error at line no 10.  

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|-

|'''too few arguments to function 'int add (int, int)' '''

|'''too few arguments to function 'int add (int, int)' '''

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|-

|Switch back to our program.  

|Switch back to our program.  

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|You can see here we have two parameters

|You can see here we have two parameters

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|'''int a '''and '''int b. '''

|'''int a '''and '''int b. '''

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|And here we are passing only one parameter.  

|And here we are passing only one parameter.  

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|Hence it is giving an error.  

|Hence it is giving an error.  

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|Let us fix the error.  

|Let us fix the error.  

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|-

|Type 4.  

|Type 4.  

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|Click on '''Save''' .  

|Click on '''Save''' .  

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|-

|Switch to the '''terminal. '''

|Switch to the '''terminal. '''

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|-

|Let us execute again.  

|Let us execute again.  

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|-

|Yes it is working!  

|Yes it is working!  

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|-

|Come back to our slides.  

|Come back to our slides.  

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|-

|To summarise, in this tutorial we have learnt -  

|To summarise, in this tutorial we have learnt -  

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|-

|'''Function'''

|'''Function'''

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|-

|Syntax of '''function'''

|Syntax of '''function'''

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|-

|'''Function without arguments'''

|'''Function without arguments'''

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|-

|Eg- void add()  

|Eg- void add()  

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|-

|Function with arguments  

|Function with arguments  

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|-

|Eg- int add(int a and  int b)  

|Eg- int add(int a and  int b)  

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|-

|As an assignment-  

|As an assignment-  

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|-

|Write a program to calculate the square of a number.  

|Write a program to calculate the square of a number.  

|-

|-

|Watch the video available at the link shown below

|Watch the video available at the link shown below

|-

|-

|It summarizes the Spoken Tutorial project  

|It summarizes the Spoken Tutorial project  

|-

|-

|If you do not have good bandwidth, you can download and watch it  

|If you do not have good bandwidth, you can download and watch it  

|-

|-

|The Spoken Tutorial Project Team  

|The Spoken Tutorial Project Team  

|-

|-

|Conducts workshops using spoken tutorials  

|Conducts workshops using spoken tutorials  

|-

|-

|Gives certificates to those who pass an online test  

|Gives certificates to those who pass an online test  

|-

|-

|For more details, please write to, contact@spoken-tutorial.org  

|For more details, please write to, contact@spoken-tutorial.org  

|-

|-

|Spoken Tutorial Project is a part of Talk to a Teacher project  

|Spoken Tutorial Project is a part of Talk to a Teacher project  

|-

|-

|It is supported by the National Mission on Education through ICT, MHRD, Government of India

|It is supported by the National Mission on Education through ICT, MHRD, Government of India

|-

|-

|More information on this Mission is available at the link shown below

|More information on this Mission is available at the link shown below

|-

|-

|This is Ashwini Patil from IIT Bombay  

|This is Ashwini Patil from IIT Bombay  

|-

|-

|Thank You for joining.

|Thank You for joining.