c - 如何从 C 中的输出中省略最后的逗号 (,)？

Question

我编写了这段代码来打印出 1 和输入值之间的所有素数:

#include <stdio.h>
#include <conio.h>

int main()
{
//Declaration of variables:
    int N, i, j, isPrime, n;

// Ask user for input the upper limit for the generation of primes (N)
printf("Enter the value of N\n");
scanf("%d",&N);

if (N==1){
    printf("There are no prime numbers before 1. Please recompile. \n" ); //print out an error if 
    // 1 is inputted as the upper limit for the generation of primes.
}

 /* For every number between 2 to N, check whether it is prime number or not */

else
    printf("The primes between 1 and %d are:  ", N);

for(i = 2; i <= N; i++){
    isPrime = 0;

        /* Check whether i is prime or not */
        for(j = 2; j <= i/2; j++){

        /* Check If any number between 2 to i/2 divides I completely If it divides, the numebr cannot be a prime. */

            if(i % j == 0){
                isPrime = 1;
                break;
            }
        }

        // print out the primes if the conditions are met

    if(isPrime == 0 && N != 1)
        printf("%d, ", i);
}

return 0;
}

效果很好，但我在每个值(包括最后一个值)后都有一个逗号。我想从最后一个逗号中删除逗号。

非常感谢您。

最好的。

Answer 1

因为确定循环的哪一次迭代是最后一次有点困难，可以将逗号放在输出的之前而不是之后并省略第一个逗号如下，为简洁起见，删除了评论。

int isFistIteraion = 0;
for(i = 2; i <= N; i++)
{
    isPrime = 0;
    for(j = 2; j <= i/2; j++){
        if(i % j == 0){
          isPrime = 1;
          break;
        }
    }
    if(IsPrime == 0 && N != 1){
        if (0 == isFirstIteration){
            isFirstIteraion = 1;
            printf("%d", i);
        } else {
            printf(", %d", i);
        }
    }
}