C + + Basic Tutorials-while Loop statements

In the previous lesson we introduced the For loop in C + +, and this tutorial introduces you to another loop statement while loop.

Let's look at another loop, which differs from the for loop in that the for loop generally knows the number of loops, which is indicated in the first row, while the while loop does not know the number of cycles, let's take a look at an exercise;

1, start Geany

1 point Menu "application-programming-geany" Start Geany, create a new C + + source program;

2 Point Menu "file-Save as" command, with "while" as the filename, save the file to its own folder;

2, input program code

1 Enter a sum of the program, when the input for the end of 0 o'clock;

#include <iostream>

using namespace Std;

int main (int argc, char** argv)

{

int a = 0;

int sum = 0;

cout << "Input a number:";

Cin >> A;

while (a!= 0)

{

sum = Sum +a;

cout << "Input a number:";

Cin >> A;

}

cout << "sum =" << sum;

return 0;

}

2 The first paragraph is the definition of two variables, storing inputs and sums,

The second paragraph is prompted to enter a value,

The third paragraph is the loop, the parentheses to determine the value of a, not 0 sum, and then continue to enter, judge, sum, until the condition does not meet the exit cycle,

The following paragraph is the result of the final sum of the output;

3 save, compile, generate, run, from the keyboard continuously input number, finally lose a 0, get the result of summation;

3 while and for loops, the while loop must first judge the condition, satisfy the recycle, generally used in reading the file, read the end of the file to exit;