5.5: for Loop Statement
- Page ID
- 126725
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"for" Loop Statement
Besides while or do-while loop statements, there are other types of looping statements. Another popular looping statement is a "for" loop statement.
The structure (syntax) of a for loop statement:
for (int i = initial_Value; i < end_Value; the statement that changes the value of i) {
Statement (s); //body of the loop
}
Example
Following is a for loop statement which displays message "Welcome to C++" on the output screen 100 times.
for(int i = 0; i < 100; i ++){
cout << "Welcome to C++\n";
}
Following flow charts demonstrate the logic of this for loop statement:
When the computer sees a for loop statement, it will initialize the variable i to 0, then evaluates the loop continuation condition i < 100, if it is a true statement, the computer goes to the body of the loop and executes those statements in the body of the loop. Upon the completion of the execution of the statements in the body of the loop, the computer executes the statement i++; to add 1 to the value of i and then re-check the loop continuation condition, if the loop continuation condition is still a true statement, then executes the statements in the body of the loop again, otherwise, move on to the next statement in the program that follows the for loop statement.
A while loop and a for loop are interchangeable. In other words, a statement or a group of statements can be repeatedly executed by either a while loop statement or a for loop statement. To help you to understand the logic of a for loop statement, we solve the same problem with a while loop and with a for loop and put two programs side by side.
Example
Write a program that displays a message "Good Morning! 5 times.
Following are two program that solve this problem, one uses a while loop and the other uses a for loop:
For this problem, the code of the program that is using for loop statement seems more compact.