fgrep.c

C语言编写的关于文件的基本 操作的程序源代码

/*-----------------------------------------------------
  Something important :
  
  char *fgets(char *buffer,int buffer_size,FILE *stream); 
  fgets read chars from the stream, and then copy it to 
  the buffer, It will stop when the '\n' be found, and it
  will stop when the size of the string is [sizeof(buf)-1]
  too.In any case, the data will keep till next call of 
  fgets.
  fgets will start read chars from what lasted last time,
  In any case, a '\0' will push into the buffer, so the 
  result of it will be a string : end by '\0'.

-------------------------------------------------------*/ 

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

#define BUFSIZE 512

void search(char *filename,FILE *stream,char *string)
{
 char buffer[BUFSIZE];

 while(fgets(buffer,BUFSIZE,stream) != NULL)
 {
  if(strstr(buffer,string) != NULL)
    {
     if(filename != NULL)
       printf("%s : ",filename);
      fputs(buffer,stdout);
    }
 }
}

int main(int argc,char **argv)
{
 char *string;
 FILE *stream;
 if(argc <= 1)
   {
    fprintf(stderr,"Usage : fgerp string file ... \n");
    exit(EXIT_FAILURE);
   }
  string = *++argv;

 if(argc <= 2)
   search(NULL,stdin,string);
 else
   {
    while(*++argv != NULL)
    {
     stream = fopen(*argv,"r");
     if(stream == NULL)
       perror(*argv);
     else
       {
        search(*argv,stream,string);
        fclose(stream);
       }
    }
   }
 return EXIT_SUCCESS;   
}