使用scanf进行分段错误

Question

noob问题:我正在尝试编写一个简单的菜单界面,但我不断收到分段错误,我无法弄清楚原因.

#include <stdlib.h>
#include <stdio.h>
int flush(); int add(char *name, char *password, char *type); int delete(char *name);
int edit(char *name, char *password, char *type, char *newName, char *newPassword, char            *newType);
int verify(char *name, char *password);



int menu(){
    int input;
    char *name, *password, *type, *newName, *newPassword, *newType;
    printf("MAIN MENU \n ============\n");
    printf("1. ADD\n");
    printf("2. DELETE\n");
    printf("3. EDIT\n");
    printf("4. VERIFY\n");
    printf("5. Exit\n");
    printf("Selection:");
    scanf("%d", &input);
    flush();
    switch (input){

    case 1:
        printf("%s\n", "Enter Name:");
        scanf("%s", name);
        flush();
        printf("%s\n", "enter password" );
        scanf("%s", password);
        flush();
        printf("%s\n","enter type" );
        scanf("%s",type);
        add(name, password, type);
        menu();
        break;
    case 2:
        printf("Enter Name:" );
        scanf("%s",name);
        flush();
        delete(name);
        menu();
        break;
    case 3:
        printf("Enter Name:\n");
        scanf("%s",name);
        flush();
        printf("Enter Password\n");
        scanf("%s", password);
        flush();            
        printf("enter type:\n");
        scanf("%s", type);
        flush();
        printf("enter your new username:\n");
        scanf("%s",newName);
        flush();
        printf("enter your new password\n");
        scanf("%s", newPassword);
        flush();
        printf("enter your new type\n");
        scanf("%s",newType);
        flush();
        edit(name, password, type, newName, newPassword, newType);
        menu();
        break;
    case 4:
        printf("Enter Name\n");
        scanf("%s",name);
        flush();
        printf("Enter Password\n");
        scanf("%s",password);
        flush();
        verify(name, password);
        menu();
        break;
    case 5:
        return 0;
    default:
        printf("invalid input, please select from the following:\n");
        menu();
}
    return 0;
    }

    int flush(){
     int ch;
     while ((ch = getchar()) != EOF && ch != '\n') ;
     return 0;
    }

在任何菜单选项中输入两个字段后,我得到分段错误

Answer 1

你需要初始化你的指针.或者,使用堆栈分配的数组.

例如,而不是char *name,做char name[20].(请注意,这会将输入限制为19个字符;如有必要,请使用更大的缓冲区.)

现在,您正在传递未初始化的指针scanf(),这有效意味着scanf()将写入未定义的内存区域.它可能在一次执行时起作用,然后在下一次执行时失败.它可能会破坏进程地址空间中其他位置的内存.

不要使用未初始化的变量,并考虑将编译器警告尽可能高地调高; 编译器可以捕获这样的错误并发出警告.