Do-while Loop in C++
Do while loop
On this page we will discuss about do while loop in C++ . Do while is a looping structure in C++, these types of loops are called Exit control or Post-test loops . In a do-while first the loop body is executed and then the test condition is checked as a result one time execution of loop body is assured even if the condition is false for the first time
Do While Loop in C++ Language
- Do while loop is very similar to the while loop. To do repetitive work control structure has been created.
- In do while we execute some statements first and then check a condition.
- That is why Do-while is known as exit controlled loop. Which means that it will be implemented atleast once
- If the condition is met we execute it again. We keep doing this until the condition keeps meeting.
Syntax:
do{
// execute statement(s)
}while(condition(s));Along with increment and initialization logic it may look like :
initialization;
do{
// execute statement(s)
incrementation;
}while(condition(s)); 
Example 1:
Run
#include<iostream>
using namespace std;
int main()
{
int i = 1000;
// i is set as 1000 which is definitely greater than 5
// the condition set below is (i <= 5) which will surely be never met
// as the loop is incrementing (i++)
// but still the loop is executed once anyways
do{
cout << i << ". Hello World\n";
i++;
}
while(i <= 5);
return 0;
}
Output:
1000. Hello World
Example 2:
#include
using namespace std;
int main()
{
int n = 25;
int i = 1;
do{
cout << i << " ";
i++;
}
while(i <= n);
return 0;
}Output:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Example 3:
Run
#include<iostream>
using namespace std;
int main()
{
int n = 100;
int i = 1;
do{
// if divisible by 7 must leave 0 remainder
// on applying modulo operator
if(i % 7 == 0){
cout << i << " ";
}
i++;
}
while(i <= n);
return 0;
}
Output:
7 14 21 28 35 42 49 56 63 70 77 84 91 98
Example 4:
#include
using namespace std;
int main()
{
char i='A';//inialisation
do
{
cout << i << " : " << (int) i << " ";
i++; // ascii codes are incremented
} while(i<='Z'); // internally ascicodes are compared
return 0;
}Output:
A : 65 B : 66 C : 67 D : 68 E : 69 F : 70 G : 71 H : 72 I : 73 J : 74 K : 75 L : 76 M : 77 N : 78 O : 79 P : 80 Q : 81 R : 82 S : 83 T : 84 U : 85 V : 86 W : 87 X : 88 Y : 89 Z : 90
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