c file handling pronblem

[snakec]

hi every body
can some one help me with thi problem
i have a text file which is following
hi Hello this is my Hello to
the Hello world
i write a code in c which is following
#include<stdio.h>
#include<string.h>
#include<stdlib.h>

void main()
{
FILE *fp,*fout;
int i=0,len_string;
char SearchText[]="Hello"; /* You can replace this text */
char ReplaceText[]="Help"; /*You can also replace this text. */
char temp[30];
fp=fopen("ram.txt","a+");
fout=fopen("temp.txt","a+");
rewind(fp); /* for going to start of file. */
if(fp==NULL || fout==NULL)
{
printf("File couldn't be opened ");
exit(0);
}
len_string=strlen(SearchText);
while(!feof(fp))
{
for(i=0;i<len_string;i++)
{ temp[i]=fgetc(fp);
}
temp[i]='\0';
if(strcmp(SearchText,temp)==0) /* the stricmp() is used for comparing both string. */
{

fprintf(fp,"%s ",ReplaceText);
fprintf(fout,"%s",ReplaceText);
fflush(fp);
fclose(fp);
fclose(fout);
exit(1);
}
}
fclose(fp);
fclose(fout);
}
now my out put is like that
hi Hello this is my Hello to
the Hello world
Help Help
what i m doing wrong ?
how to replace Hello to help in my text file ?
how to get my output like that?
hi Help this is my Hello to
the Help world
can anybody explain with code ?

[kooth]

For your input file, you should use "r" (read-only). Does your output file exist already? If so, you will want to open it with r+. If not, you will need to write all of the contents from your input file to the output file.

Also, you should move your rewind( fp ) to after you check for a null pointer.

[kooth]

Also, put some printf statements in your code to see what temp is after you place the NULL byte into it. You will be surprised by what you see!

[madredcake]

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

#define max_temp 30

int main()
{
  FILE *fp,*fout;
  int i;
  char SearchText[]="Hello"; /* You can replace this text */
  char ReplaceText[]="Help"; /*You can also replace this text. */
  char temp[max_temp];

  fp=fopen("ram.txt","r");  //"r" opens file at the begining -> no need for rewind( fp ) 
  fout=fopen("temp.txt","w");

  if(fp==NULL || fout==NULL){
    perror("File couldn't be opened ");
  }


  fscanf(fp,"%s",temp);  

  while(!feof(fp)){
    if(strcmp(SearchText,temp)==0)
      fprintf(fout,"%s ",ReplaceText);
    else
      fprintf(fout,"%s ",temp);

    fscanf(fp,"%s",temp);
  }

  fclose(fp);
  fclose(fout);
  return 0;
}

The part

 fscanf(fp,"%s",temp);  

  while(!feof(fp)){
    if(strcmp(SearchText,temp)==0)
      fprintf(fout,"%s ",ReplaceText);
    else
      fprintf(fout,"%s ",temp);

    fscanf(fp,"%s",temp);
  }

may seem to be weird but if you use

  while(!feof(fp)){
    fscanf(fp,"%s",temp);

    if(strcmp(SearchText,temp)==0)
      fprintf(fout,"%s ",ReplaceText);
    else
      fprintf(fout,"%s ",temp);
  }

the last word in the input file ("world" in your case) will be printed 2 times

[kooth]

Nice work, madredcake! It's concise and you took out a couple of bugs too!

[filipe]

Don't use fscanf like that. What if it reads more than can fit in temp? You'll have a buffer overrun. If you insist on using it, at least pass fscanf how much it should read:

fscanf(fp, "%29s", temp);

[kooth]

Good job, filipe!