c - 单独的部分可以正常工作，但是当合并时会导致崩溃

Question

该程序在单独编辑时有效，在单独读取时也有效:

    printf("Enter the name of file you wish to edit:\n");
    gets(file_name); //file_name = input

    file = fopen(file_name,"w"); // write mode

   if( file == NULL ) //If file couldn't be opened
   {
      perror("Error while opening the file!\n");
      exit(EXIT_FAILURE);
   }

    printf("Enter name: \n"); scanf("%s",name1);
    printf("Enter second name if applicable: \n"); scanf("%s",name2);
    printf("Enter grade: \n"); scanf("%s",grade);
    fprintf(file, "%s%s%s\t%s%s%s", name1, " ", name2, "=", " ", grade);
    fclose(file);
    printf("File write was successful\n");

和

   printf("Enter the name of file you wish to see:\n");
   gets(file_name); //file_name = input

   file = fopen(file_name,"r"); // read mode

   if( file == NULL ) //If file couldn't be opened
   {
      perror("Error while opening the file!\n");
      exit(EXIT_FAILURE);
   }

   printf("The contents of %s file are:\n", file_name);

    while( ( character = fgetc(file) ) != EOF /*EOF = End Of File*/)
        printf("%c",character); //print c (character)

   fclose(file); //remove the file from RAM

但是，当它们与 if 放在一起时，只要将 1 或 2 输入到第一部分，程序就会崩溃:

 printf("Edit or Read file? (1 for edit, 2 or read)\n"); scanf("%s",RW);

完整代码如下:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
    char character, file_name[25];
    int RW;
    const char *quit;
    FILE *file; //"file" stores file stream
    char data [100000];
    char name1 [100000];
    char name2 [100000];
    char grade [100000];

    printf("Edit or Read file? (1 for edit, 2 or read)\n"); scanf("%s",RW);

    if (RW == 1)
    {
       printf("Enter the name of file you wish to see:\n");
       gets(file_name); //file_name = input

       file = fopen(file_name,"r"); // read mode

       if( file == NULL ) //If file couldn't be opened
       {
          perror("Error while opening the file!\n");
          exit(EXIT_FAILURE);
       }

       printf("The contents of %s file are:\n", file_name);

        while( ( character = fgetc(file) ) != EOF /*EOF = End Of File*/)
            printf("%c",character); //print c (character)

       fclose(file); //remove the file from RAM
    } else if ( RW == 2) {

        printf("Enter the name of file you wish to edit:\n");
        gets(file_name); //file_name = input

        file = fopen(file_name,"w"); // write mode

       if( file == NULL ) //If file couldn't be opened
       {
          perror("Error while opening the file!\n");
          exit(EXIT_FAILURE);
       }

        printf("Enter name: \n"); scanf("%s",name1);
        printf("Enter second name if applicable: \n"); scanf("%s",name2);
        printf("Enter grade: \n"); scanf("%s",grade);
        fprintf(file, "%s%s%s\t%s%s%s", name1, " ", name2, "=", " ", grade);
        fclose(file);
        printf("File write was successful\n");
    }

    printf(" \n");
    printf("Close window?\n"); scanf("%s",quit);
    if (quit == "y")
    {
        printf("Bye!\n");
    }
    return (0);
}

Answer 1

发布的程序因为这一行而崩溃:

scanf("%s",RW);

变量 RW 声明为 int。

对 scanf() 的调用需要一个指向 char 数组的指针。

所以代码试图将 RW 作为一个指针，并跟随该指针(它包含堆栈中 RW 位置的垃圾。那是导致崩溃的原因。

建议将语句写成:

scanf("%u",&RW);