Question

我的程序如下，我正在尝试在visual studio上运行它并且它一直给我一个错误Illegal if Without matching if。

我相信它试图告诉我，我的else与if不符，但确实如此。以下是我的代码;有人可以运行它，让我知道问题是什么，所以我将来不再重复它了吗？

/* counting number of students that pass*/
#include <stdio.h>

main()
{
    int pass, fail, grade;
    printf(" This program  tells you total number of students that passed\n Enter -1 to finish the program");

    pass = 0;
    fail = 0;
    grade = 0;

    while (grade != -1) {           /* Enter -1 to finish the while loop*/
        printf("Enter the grade of the student, 1 is pass, 2 is fail, -1 finishes the program\n");
        scanf_s("%d", &grade);
        if (grade == 1)
            printf("The student passed\n");
        pass = pass + 1;                /* Add 1 to the pass*/
        else if (grade == 2)
            printf("The student failed\n");
        fail = fail + 1;            /*Add 1 to fail */
        else
            printf("You have entered an invalid number, please try again\n");
    }

    if (pass > 8)
        printf("More than 8 students passed; raise tuition fees\n");

    getchar();
}

Answer 1

大括号是你的朋友。更改代码段

if (grade == 1)
    printf("The student passed\n");
pass = pass + 1;                /* Add 1 to the pass*/
else if (grade == 2)
    printf("The student failed\n");
fail = fail + 1;

到

if (grade == 1){
    printf("The student passed\n");
    pass = pass + 1;                /* Add 1 to the pass*/
}
else if (grade == 2){
    printf("The student failed\n");
    fail = fail + 1;
}

Answer 2

    if (grade == 1)
        printf("The student passed\n");
    pass = pass + 1;

代码pass = pass + 1;不在if语句下，你需要多个语句的大括号：

if (grade == 1)
{
    printf("The student passed\n");
    pass = pass + 1; 
} 


else if (grade == 2)
{
   printf("The student failed\n");
   fail = fail + 1;            /*Add 1 to fail */
}

Answer 3

除非您使用大括号来定义if的开始和结束位置，否则语句pass = pass +1;将在您的if之外：

    if (grade == 1)
    {
        printf("The student passed\n");
        pass = pass + 1;                /* Add 1 to the pass*/
    }
    else if (grade == 2)

否则如果C语句不能按预期工作

3 个答案: