For Loops
C++ for Loop Syntax
where, only testExpression is mandatory.
How for loop works?
The initialization statement is executed only once at the beginning.
Then, the test expression is evaluated.
If the test expression is false, for loop is terminated. But if the test expression is true, codes inside body of
for
loop is executed and update expression is updated.Again, the test expression is evaluated and this process repeats until the test expression is false.
Flowchart of for Loop in C++
Example 1: C++ for Loop
Output
In the program, user is asked to enter a positive integer which is stored in variable n(suppose user entered 5). Here is the working of for
loop:
Initially, i is equal to 1, test expression is true, factorial becomes 1.
i is updated to 2, test expression is true, factorial becomes 2.
i is updated to 3, test expression is true, factorial becomes 6.
i is updated to 4, test expression is true, factorial becomes 24.
i is updated to 5, test expression is true, factorial becomes 120.
i is updated to 6, test expression is false,
for
loop is terminated.
In the above program, variable i is not used outside of the for
loop. In such cases, it is better to declare the variable in for loop (at initialization statement).
Check out these examples to learn more:
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