From Script | Spoken-Tutorial
Revision as of 12:15, 16 August 2013 by Sneha
|00.02||Welcome to the spoken tutorial on Conditional statements in C and C++|
|00.09|| In this tutorial we will learn,
|00.11|| how to execute a single statement.
|00.14|| How to execute group of statements.
|00.17|| We will do this through examples.
|00.20||We will also see some common errors and their solutions.|
|00.25|| To record this tutorial, I am using, Ubuntu Operating system version 11.10.
|00.32||gcc and g++ Compiler version 4.6.1|
|00.38|| Let us start with the Introduction to condition statements.
|00.43|| A statement in a program controls the flow of program execution.
|00.50|| It helps to make decision on, what code is to be executed.
|00.56||We can check the conditions, whether true or false.
|01.01||We can execute a single statement or a group of statements.|
|01.08|| Let us understand the flow of if statements.
|01.13|| Here, if the condition is true then , statement1 will be executed.
|01.20||If the condition is false then statement2 will be executed.|
|01.29|| Now we will see the flow of else if statement,
|01.32|| Here, if condition1 is true then statement1 will be executed.
|01.41|| If condition1 is false then it will check for another condition that is condition2.
|01.50|| If condition2 is true, then statement3 will be executed.
|01.55||And If condition2 is false, then statement2 will be executed|
|02.03|| Now Let us move on to our program.
|02.06|| I have already typed the code on the editor.
|02.09|| So let me open it.
|02.13||Note that our filename is ifstmt.c|
|02.19||In this program we will calculate the sum of two numbers and will check a few conditions.|
|02.27|| Let me explain the code now.
|02.31||This is our header file.|
|02.34||This is our main function.|
|02.38||Here we have declared three integer variables a, b and sum.|
|02.47|| Here we are asking for user input.
|02.49|| User will enter the values of a and b.
|02.52||The values will be stored in variable a and variable b.|
|02.58||The 'scanf() reads data from the console.
|03.02|| It then stores the result in the given variable.
|03.06|| The format specifier in the scanf() helps to know the type of data.
|03.11||Like here we have %d it denotes that we are dealing with integer data type.|
|03.19|| Here we add the values of a and b.
|03.22||We will store the result in sum.|
|03.26||Then we print the result.|
|03.29||This is our if statement.|
|03.31||Here, we check the condition whether sum is greater than 20.|
|03.36||If the condition is true, then we print Sum is greater than 20.|
|03.43||Now let me comment out these lines.|
|03.48||This is our return statement.|
|03.51||Now click on Save|
|03.53||First we will see the execution of if statement.|
|03.58||Please open the terminal window by pressing,Ctrl, Alt and T keys simultaneously on your keyboard.|
|04.09||To compile type, gcc ifstmt.c -o ifand press enter|
|04.20||To execute type, ./if press enter|
|04.26||it is displayed as,|
|04.27||Enter the value of a and b.|
|04.32||I will give the values as 10 and 12.|
|04.38||The output is displayed as Sum of a and b is 22. Sum is greater than 20.|
|04.45||Now come back to our program.|
|04.49||We will check another condition.|
|04.53||Let me remove the comment from here.|
|04.57||I will give the comment here.|
|05.00||Now click on Save.|
|05.03||This is our else-if statement.|
|05.05||Here, we check another condition whether Sum is greater than 10|
|05.11||If the condition is true. Then we print Sum is greater than 10 and less than 20.|
|05.18||Now come back to our terminal.|
|05.20||Let us compile as before. Let us execute as before.|
|05.27||It is displayed as,|
|05.28||Enter the value of a and b.|
|05.30||I will give the values as 10 and 2.|
|05.35||The output is displayed as: Sum of a and b is 12.|
|05.39||Sum is greater than 10 and less than 20.|
|05.43||Let me clear the prompt. Now come back to our program.|
|05.48||I will remove the comment from here and here.Now click on save,|
|05.56||If both the conditions are false, then we print Sum is less than 10.|
|06.04||This is our else statement.|
|06.08||Now let us execute and see. come back to our terminal.|
|06.12||Let us compile as before. Let us execute as before.|
|06.18||Here it is displayed as,|
|06.19||Enter the value of a and b.|
|06.22||I will give the values as 3 and 5.|
|06.27||the output is as, sum of a and b is 8.|
|06.31||Sum is less than 10.|
|06.34||Now we will see some common errors which we can come across.|
|06.38||Come back to our program.|
|06.41||Suppose, here at the end of if statement I will type a semicolon.|
|06.47||Let see what will happen.Click on Save.
|06.50||Let us execute. Come back to our terminal.|
|06.53||Let us compile as before.|
|06.56||We see an error: else without a previous if|
|07.02||Come back to our program.It is an syntax error.|
|07.07||If statement will never terminate with a semicolon.|
|07.10||And the else if statement will never work without an if.|
|07.16||Let us fix the error. Delete the semicolon ; here|
|07.22||Now Click on Save.|
|07.25||Let us execute. Come back to the terminal.|
|07.29||Let us compile as before. Let us execute as before.|
|07.35||Enter the value of a and b|
|07.37||I will give the values as 3 and 6.|
|07.44||The output is displayed as|
|07.46||Sum of a and b is 9. Sum is less than 10.|
|07.52||NOW WE WILL SEE HOW TO EXECUTE THE SAME PROGRAM IN C++.|
|07.57||Come back to our program.|
|08.00||I will change a few things here.|
|08.03||Press Shift, Ctrl and S keys simultaneously on your keyboard.|
|08.11||Now save the file with an extension .cpp and click on Save|
|08.20||We will change the header file as, iostream|
|08.26||Let us include the using statement here.|
|08.30||Now click on the search for and replace text option .|
|08.36||let us replace printf statement with cout statement.|
|08.40||Click on Replace all and click on Close
|08.46||Now delete the closing brackets here.|
|08.50||Replace the scanf statement with the cin statement.|
|08.54||Type cin and two closing angle brackets >>|
|09.00||As we use cin >> function to read a line in C++.
|09.06||Now delete the format specifiers.|
|09.09||Delete the comma and ampersand &|
|09.12||Delete the comma here and type two closing angle brackets.|
|09.17||Again delete the ampersandand the closing brackets. Now Click on Save.|
|09.25||Here delete the closing bracket and the comma.|
|09.32||Now delete the 'backslash n' and 'format specifier
|09.37||Now Type two opening brackets|
|09.42||Again type two opening angle brackets and within the double quotes type backslash n “\n”.|
|09.49||Here also we will delete the closing bracket.|
|09.54||Now again delete the closing bracket here and here.|
|09.59||Now Click on Save|
|10.03||Let us execute.|
|10.04||Come back to the terminal.let me clear the prompt.|
|10.10||To compile type g++ space ifstmt.cpp space -o space if1|
|10.21||Here we have if1 because we don't want to overwrite the output parameter if for the file ifstmt.c|
|10.31||Now Press Enter|
|10.33||To execute type ./if1 and Press Enter|
|10.39||Enter the value of a and b. I will give the values as 20 and 10.|
|10.48||The output is displayed as, Sum of a and b is 30.|
|10.53||Sum is greater than 20.|
|10.56||This brings us to the end of this tutorial.|
|10.59||Now come back to our slides.|
|11.03||Let us summarize.|
|11.04||In this tutorial we learned, if statement eg. if(condition)
|11.12|| And else if statement eg. else if(condition)
|11.18||As an assignment,|
|11.19||Write a program to check a is greater than b or less than b.|
|11.24||Hint: use if statement.|
|11.28||Write another program to check which value is greater a, b or c.|
|11.34||Hint: use else-if statement.|
|11.39||Watch the video available at the link shown below. http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial|
|11.41||It summarizes the Spoken Tutorial project.|
|11.44||If you do not have good bandwidth, you can download and watch it.|
|11.49||The Spoken Tutorial Project Team,|
|11.51||Conducts workshops using spoken tutorials.|
|11.54||Gives certificates to those who pass an online test.|
|11.58||For more details, please write to, contact [at] spoken hyphen tutorial dot org.|
|12.05||Spoken Tutorial Project is a part of the Talk to a Teacher project.|
|12.09||It is supported by the National Mission on Education through ICT, MHRD, Government of India.|
|12.16||More information on this Mission is available at the link shown below. (http://spoken-tutorial.org\NMEICT-Intro)|
|12.21|| This is Ashwini Patil from IIT Bombay
Thank You for watching.