使用字符串，指針和函數在C中獲取分段錯誤

Question

編輯：解決了它，原來我應該使用 %c 而不是 %s 因為foodSelect和foodSize是不是字符串的字符：P謝謝

我試圖將3個值傳遞給函數output ：foodChoice，foodSelect，foodSize（以及foodOrderNum和foodSubtotal，但我還沒有解決這個問題）。

但是，當我嘗試foodSelec t時，出現了段錯誤，但是當我嘗試打印foodChoice ，卻沒有。 當我嘗試printf foodSize它什么也沒顯示。

資源：

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

void question (char choice[]);
int output(char *foodChoice, char *foodSelect, char *foodSize);


void question (char choice[]) {

    char choiceYesNo;
    char *foodOptions;
    char *foodChoice;
    char *foodSelect;
    char *foodSize;
    int foodOrderNum = 0;
    float foodSubtotal = 0;

    switch (choice[0]) {
        case 'f':
            foodChoice = "Fish";
            foodOptions = "(K- Haddock, T- Halibut)";
            break;
        case 'c':
            foodChoice = "Chips";
            foodOptions = "(C- Cut, R- Ring)";
            break;
        case 'd':
            foodChoice = "Drinks";
            foodOptions = "(S- Softdrink, C- Coffee, T- Tea)";
            break;
    }

    printf("Do you order %s? (Y/N): ", foodChoice);
        scanf("%c", &choiceYesNo);
    printf("%s choice %s: ", foodChoice, foodOptions);
        scanf("%s", &foodSelect);
    printf("What size (L - Large, M - Medium, S - Small): ");
        scanf("%s", &foodSize);
    printf("How many orders do you want? (>=0): ");
        scanf("%d", &foodOrderNum);
    output(foodChoice, foodSelect, foodSize);
}

int output(char *foodChoice, char *foodSelect, char *foodSize) {

    // printf("You ordered %s: %s - SIZE: %s   amount ordered: , subtotal price: \n", 
    // foodChoice, foodSelect, foodSize);

    printf("\n\n%s\n", foodSelect);
    // printf("\n\n%s\n", foodSelect);

}

int main() {

    question("chips");


}

Answer 1

您尚未為以下項分配內存：

char * foodOptions; char * foodChoice; char * foodSelect; char * foodSize;

執行malloc並分配內存。 注意：

char *foodChoice="Fish";

和

char *foodChoice;
foodChoice="Fish";

不一樣。

Answer 2

這是因為您將&foodSelect傳遞給scanf ，這對於C字符串是不正確的。 您應該通過foodSelect代替，不要使用＆號。

您還應該分配足夠的空間來存儲用戶輸入的值，並指示scanf有關緩沖區的最大大小。

#define MAX_BUF 128

...
char foodSelect[MAX_BUF];
...
scanf("%127s", foodSelect);