无法使用C语言读取文件。 它创建一个新文件，而不是读取它

Question

I have creates a file in directory and want to read it in. I am using the following code to open and read a file in C-Language. But it creates a new file instead of reading the old file.

int main()
{
   FILE * file;
   file = fopen ("file", "r+");
   //file reading code
   fclose(file);
   return(0);
}

Answer 1

you are using 'r+' mode to open the file. It creates a new file if not already exist in the directory. see the following code for your help.

int main()
{
   FILE * file;
   file = fopen ("file", "r");
   if(file !== NULL)
       // to do file reading code
   else 
       printf("error in reading file");
   fclose(file);
   return(0);
}

also check the file name that you are using in fopen() function.It is case sensitive and also check the extension of that file eg; .txt or .data or what ever. eg;

file = fopen ("File.txt", "r");

Answer 2

如果您只打算从文件中读取文件，则将其打开以进行读取，即模式r （注意no + ）：

file = fopen ("file", "r");

Answer 3

I agree with answers given but you can also additionally check if file is present or not. Something as below. In case program does not recognize the file it will let you know. Avoid using r+ in case you want to read an already existing file.

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

int main()
{
   char ch, file_name[25];
   FILE *fp;

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

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

   if( fp == NULL )
   {
      perror("Error while opening the file.\n");
      exit(EXIT_FAILURE);
   }

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

   while( ( ch = fgetc(fp) ) != EOF )
      printf("%c",ch);

   fclose(fp);
   return 0;
}