（while述句）求不定个数正整数和

#include <stdio.h>
int main()
{
    int number;
    int sum = 0;
    printf("Please enter the numbers (0: quit):
"); 
    scanf("%d", &number);
    while (number != 0)
    {
        sum = sum + number;
        scanf("%d",&number);
    }
    printf("The sum is %d.
",sum);
    return 0;
}

Please enter the numbers (0: quit):
12
34
56
78
89
0
The sum is 269.

Process returned 0 (0x0)   execution time : 7.443 s
Press any key to continue.

do-while 和 while的区别在于do-while至少做一次

#include <stdio.h>
int main() {
    int count = 3;
    do{
        printf("%d
", count);
        count++;
    } while (count < 3);
    return 0;
}


3

Process returned 0 (0x0)   execution time : 10.465 s
Press any key to continue.

而如果是while的话不执行

#include <stdio.h>
int main() {
    int count = 3;
    while (count < 3) {
        printf("%d
", count);
        count++;

    }

    return 0;
}



Process returned 0 (0x0)   execution time : 8.925 s
Press any key to continue.