c - 如何避免C中的sscanf()引起无限的while循环，而不是存储用户输入？

Question

我一直工作在C项目，而现在，我是相当新的C，我现在尝试过许多东西，但似乎没有任何工作。每当我进入while循环并进入sscanf（）函数时，循环就会变成无限循环，并且无法接收输入。意思是说我不能抓住，并将其存储在MT二维数组

我也尝试过使用strtok（）作为另一个选项，但是代码变得太乱了。

typedef struct item {
    char name[50];
    double price;
} item;


int main() {
    // 1 begins
    char userInput[100];
    printf("Hello, welcome to the shelf-O-matic!\n");

    printf("Please press enter and then type the number of shelves followed by ',' and number of slots\n");
    int shelf = 0;
    int slot = 0;
    scanf("%d , %d", &shelf, &slot);

    struct item **thing = malloc(shelf * sizeof(item));
    for (int i = 0; i < slot; i++) {
        thing[i] = malloc(slot * sizeof(item));
    }
    while (strcmp(userInput , "quit")!= 0) {

        //variables symbolizing the slots and shelves
        printf("type quit to exit or set input to the array\n");
        //scanf("%100s", userInput);

        //Putting the size in memory location


        double *cash = malloc(sizeof(cash));
        int *x = malloc(sizeof(x));
        int *y = malloc(sizeof(y));
        //scanf("%100s", userInput);

        // 1 ends
        char *itemName = malloc(sizeof(itemName));
        printf("Please add things to the shelves and slots by specifying <name> <price> <shelf> <slot> or type quit to finish adding\n");
        sscanf(userInput,"%100s, %lf, %d, %d", itemName, &cash, &x, &y);

     printf(itemName);
     printf(cash);
     printf(x);
     printf(y);


}

    return 0;
    }

预期结果应该是输入到内存中的输入，以便随后可以将其分配给数组值并打印出来以进行验证。

Answer 1

while循环是无限的，部分原因是因为对输入的请求已被注释掉并且sscanf没有任何内容可解析。
另一个问题可能是使用%s解析itemName。如果在空间itemName，％s将会停止在第一空间。如果要使用逗号来分隔值，则%s会将逗号视为itemName的一部分而视为另一个字符。
扫描集可以帮助您。 scanset %[^,]告诉sscanf扫描不是逗号的字符并将其放在itemName中。因此，%49[^,],将最多扫描49个不是逗号的字符，然后再扫描逗号。
考虑对所有输入使用fgets并使用sscanf进行解析。其他一些有用的解析函数是strtol，strtod，strspn和strcspn。还有更多。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct item {
    char name[50];
    double price;
} item;

int main ( void) {
    char userInput[100];
    int result = 0;
    int shelf = 0;
    int slot = 0;

    printf ( "Hello, welcome to the shelf-O-matic!\n");
    do {
        printf ( "Please enter the number of shelves\n");
        if ( fgets ( userInput, sizeof userInput, stdin)) {
            result = sscanf ( userInput, "%d", &shelf);
        }
        else {
            fprintf ( stderr, "fgets EOF\n");
            return 0;
        }
    } while ( 1 != result || 0 >= shelf);
    printf ( "shelf = %d\n", shelf);
    do {
        printf ( "Please enter the number of slots\n");
        if ( fgets ( userInput, sizeof userInput, stdin)) {
            result = sscanf ( userInput, "%d", &slot);
        }
        else {
            fprintf ( stderr, "fgets EOF\n");
            return 0;
        }
    } while ( 1 != result || 0 >= slot);
    printf ( "slot = %d\n", slot);
    //allocate pointers then allocate structures to the pointers
    struct item **thing = malloc ( sizeof *thing * shelf);
    if ( NULL == thing) {
        fprintf ( stderr, "malloc problem\n");
        return 0;
    }
    for (int i = 0; i < shelf; i++) {//iterate through shelf number of pointers
        thing[i] = malloc( sizeof **thing * slot);
        if ( NULL == thing[i]) {
            fprintf ( stderr, "malloc problem\n");
            return 0;
        }
    }

    while ( 1) {//keep looping
        double cash = 0.0;
        int x = 0;
        int y = 0;
        char itemName[50] = "";

        result = 0;
        printf ( "Please add things to the shelves and slots\n");
        printf ( "specify:        name, price, shelf, slot\n");
        printf ( "when finished type quit or exit\n");
        if ( fgets ( userInput, sizeof userInput, stdin)) {//get input
            if ( ( strcmp ( userInput, "quit\n") == 0)
            || ( strcmp ( userInput, "exit\n") == 0)) {//exit loop
                break;
            }
            result = sscanf ( userInput, "%49[^,], %lf ,%d ,%d"
            , itemName, &cash, &x, &y);//sscanf to parse input

            if ( 4 == result
            && 0 < x && x < shelf
            && 0 < y && y < slot) {//scanned four items. shelf slot in range
                printf ( "%s\n", itemName);
                printf ( "%f\n", cash);
                printf ( "%d\n", x);
                printf ( "%d\n", y);

                //store in thing[x][y]
            }
            else {
                printf ( "\n\tproblem with input.");
                if ( 0 > x || x >= shelf) {
                    printf ( " bad shelf.");
                }
                if ( 0 > y || y >= slot) {
                    printf ( " bad slot.");
                }
                printf ( " try again\n\n");
            }
        }
        else {
            fprintf ( stderr, "fgets EOF\n");
            //free structures then the pointers
            for (int i = 0; i < shelf; i++) {
                free ( thing[i]);
            }
            free ( thing);

            return 0;
        }
    }
    //free structures then the pointers
    for (int i = 0; i < shelf; i++) {
        free ( thing[i]);
    }
    free ( thing);

    return 0;
}