声明不适用于for循环

Question

“我遇到的实际问题是它在发出问题数量后才停止运行。我已将”％d％“更正为”％d“并且仍然存在问题”

我正在开展一个项目，在那里我做一个小型的数学游戏。 我需要提示一个难度（简单，硬或退出）级别，然后是一个类别（加法，减法，乘法和除法）。我的菜单工作正常但我似乎无法得到任何声音

printf (" How many questions would you like to attempt?\n");
scanf ("%d%", &numofquestions);

上班。 谁能告诉我我做错了什么？ 下面是我到目前为止的完整代码，那里有一些不必要的项目，但据我所知，它们不是问题。

/* Program Description Goes Here */
#include <stdio.h>
#include <stdlib.h>

 /* function main begins program execution */
int main( void )
{
    /* Main Code Area For Program */
int difficulty = -1;
int category = 0;
int numofquestions;
int ca = 0; /* Correct Answer */
int cc; /* Correcnt Counter */
int ran1;
int ran2;
int random1 = 0;
int random2 = 0;
int usera; 
int i;
/* Welcome mesage */
srand ( time (NULL));

printf ( "Welcome to the math challenge.\n"); 


while ( difficulty != 1 && difficulty != 2 && difficulty !=0){ 

    printf ("Select 1 for Easy\n");
    printf ("Select 2 for Hard\n");
    printf ("Select 0 to Quit\n");
    scanf ( "%d", &difficulty);
}

        while ( category != 1 && category != 2 && category != 3 && category != 4){

    category = getchar();
    switch (category){
        case 'A':
        case 'a':
            category = 1;
            break;
        case 'S':
        case 's':
            category = 2;
            break;
        case 'M':
        case 'm':
            category = 3;
            break;
        case 'D':
        case 'd':
            category = 4;
            break;
        case '/n':
        case '/t':
        case ' ':
            break;
        default:
            printf ("Enter A for Addition\n");
            printf ("Enter S for Subtraction\n");
            printf ("Enter M for Multiplication\n");
            printf ("Enter D for Division\n");
    }
}

        printf (" How many questions would you like to attempt?\n");
        scanf ("%d%", &numofquestions);


        for (i = numofquestions; i<=0; --i){/* start for */

            if ( difficulty == 1){ /* start if */
                random1 = (rand () % 10);
                random2 = (rand () % 10);

                }/* end if */ 

            if ( category == 1){/* start if */
                printf ( "%d + %d = ?" , random1 , random2 );
                ca = random1 + random2;
                printf ( "Your response\n");
                scanf ( "%d", &usera);
                                }/* end if */

            if ( usera == ca ){ /* start if */
                printf (" %d\n ", ca);
            }/* end if */


        /* end for */}


return 0; /* indicate that program ended successfully */
/* end function main */
}

Answer 1

删除重复的% in：

scanf("%d%", &numofquestions);

应该：

scanf("%d", &numofquestions);

Answer 2

这是额外的％d * ％ *故意吗？

scanf（“％d％”，＆numofquestions）;

for（i = numofquestions; i <= 0; --i）{/ * start for * / this应为（i = numofquestions; i> = 0; - i）我想！

Answer 3

getchar()返回一个int，你的switch语句返回check char。 http://www.cplusplus.com/reference/cstdio/getchar/

%d%应为%d 。 for (i = numofquestions; i<=0; --i){得到一个int。 这只会在数字为0或更小时运行，然后才能永久运行。