Question

我不确定我做错了什么，但for循环没有初始化代码只是立即显示printfs。因为for循环没有激活

，所以没有值

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#define PAUSE system("Pause")

main() {
    // INITALIZE VARIABLES 
    int number = 0;
    int i = 0;
    int odd = 0;
    int even = 0;
    int totalNum = 0;
    int tempNum = 0;
    int count;

    printf("Enter a number between 2 and 25\n");
    scanf("%i", &number);

    do{
        if (number < 2 || number > 25)
            printf("That was an invalid number please try again\n");
            scanf("%i", &number);
    } while (number < 2 || number > 25);

    printf("Enter how many numbers you want to input\n");
    scanf("%i", &count);

    for (i = 1; i == count; ++i){
        printf("input numbers\n");
        scanf("%i", &tempNum);
        if (tempNum % 2 == 0)
            even++;
        else
            odd++;
        totalNum = totalNum + tempNum;
    } // END FOR LOOP

    // DISPLAY OUTPUT
    printf("You entered %i numbers\n", count);
    printf("The sum of the %i numbers is %i\n", count, totalNum);
    printf("The average of the %i numbers is %i\n", count, totalNum / count);
    printf("You entered %i odd numbers and %i even numbers\n", odd, even);

    PAUSE;
} // END MAIN

Answer 1

当您将count == 1初始化为i时1，您的循环最多只会执行一次。

如果您为计数输入1，

   printf("Enter how many numbers you want to input\n");
   scanf("%i", &count);

循环将只运行一次，直到i递增到2

你可能想要：

for (i = 1; i <= count; ++i){

Answer 2

do{
    if (number < 2 || number > 25)
        printf("That was an invalid number please try again\n");
        scanf("%i", &number);
} while (number < 2 || number > 25);

它应该是......

do{
    if (number < 2 || number > 25){
        printf("That was an invalid number please try again\n");
        scanf("%i", &number);
    }
} while (number < 2 || number > 25);

否则它总是要求另一个号码

Answer 3

i = 1，因此i == count;会false，因此会忽略循环。

Answer 4

C中的for循环的工作原理如下：

for ( variable initialization; condition; variable update ) {
    /* Do something... */
}

只要条件为真，循环就会执行。所以，当你这样做时：

for (i = 1; i == count; ++i)

只要 i == count 为真，循环就会执行。因此，除非 count 在执行此行时保持 1 ，否则循环将永远不会运行。

正如其他人指出的那样，你可能想要这个：

for (i = 1; i <= count; ++i)

因此，您的循环将针对 i 的所有值运行，直到达到计数。

作为旁注，我应该指出在C中编写for循环的通常方法是这样的：

for (i = 0; i < count; i++)

我们从 i = 0 开始，因为C数组是从零开始的，所以数组的第N个元素的索引 n-1

Answer 5

你太近了。除了修复循环测试条款for (i = 1; i <= count; i++)之外，我建议您使用" %d"作为格式说明符。您的do循环只需要while循环，以避免每次都打印invalid number消息。

此外，虽然不是错误，但C的标准编码样式避免使用caMelCase变量来支持所有小写。参见例如NASA - C Style Guide, 1994

通过这些更改，（并将奇数/偶数检查更改为简单的&），您可以按如下方式编写代码。

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
// #define PAUSE system("Pause")

int main (void)
{
    int number, i, odd, even, totalnum, tempnum, count;
    number = i = odd = even = totalnum = tempnum = count = 0;

    printf ("enter a number between 2 and 25: ");
    scanf (" %d", &number);

    while (number < 2 || number > 25) {
        printf ("invalid number, again (between 2 and 25): ");
        scanf (" %d", &number);
    }

    printf ("numbers to input: ");
    scanf (" %d", &count);

    for (i = 1; i <= count; i++) {
        printf ("input number %2d: ", i);
        scanf (" %d", &tempnum);
        if ((tempnum & 1) == 0)
            even++;
        else
            odd++;
        totalnum = totalnum + tempnum;
    }

    printf ("You entered %d numbers\n", count);
    printf ("The sum of the %d numbers is %d\n",
            count, totalnum);
    printf ("The average of the %d numbers is %d\n",
            count, totalnum / count);
    printf ("You entered %d odd numbers and %d even numbers\n",
            odd, even);

//     PAUSE;
    return 0;
}

注意： main是int类型（例如int main (int argc, char **argv)或简称int main (void)，表示没有参数）。由于它是int类型，它将return一个shell的值。虽然历史实现可能允许void main不再适用于可移植代码。

示例使用/输出

$ /bin/forskipped
enter a number between 2 and 25: 4
numbers to input: 4
input number  1: 1
input number  2: 2
input number  3: 3
input number  4: 4
You entered 4 numbers
The sum of the 4 numbers is 10
The average of the 4 numbers is 2
You entered 2 odd numbers and 2 even numbers

仔细看看，如果您有任何问题，请告诉我。

为什么这个for循环被忽略了？

5 个答案: