Thread: FILE pointer problem

Read the output of a file as

ABCDEFGHIFSFSA
1242487132
FSFSA
*


a) Print the output as

*
FSFSA
1242487132
ABCDEFGHIFSFSA

b) Print the output as
*
AFFSS
1122234478
AABCDEFFFGHISS

HELP NEEDED URGENT!!!!!

Code:

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
int main()
{
	FILE *fp1,*fpo;
	char s[20][100],ch;
	int i,j;
	fp1=fopen("pr31.c","w");
	if(fp1==NULL)
	{
		printf("cannot open file");
	}
	while(strlen(gets(s))>0)
	{
		fputs(s,fp1);
		fputs("\n",fp1);
	}
	printf("file closed\n\n");
	fpo=fopen("pr32.c","w");
	ch=fgetc(fp1);
	i=j=0;
	while(!feof(fp1))
	{
		if(ch=='\n')
		{
			s[i][j]='\0';
			i++;
			j=0;
		}
		else
		{
			s[i][j]=ch;
			j++;
		}
		ch=fgetc(fp1);
	}
	for(j=0;j<i;j++)
		printf("%c",s[j]);
	getch();
	return 0;
}

its not compiling......

Are you sure ? it compiles for me.
whats the error message you are getting ?

my prog is writing to the file and reading from it the array of strings...
though it is compiling i am not getting the output correctly

i am compiling in turbo c++4.5
i m getting general protection exception

i need it urgent pls someone post me whole correct code

i am compiling in turbo c++4.5
i m getting general protection exception

=>BEN10
yes i did but still the general protection exception is occuring

printf("file closed\n\n");

Umm, you do know you actually have to close the file right ?

Code:

fclose(fp1);

Also, change your while loop to this and remove the fgetc at the bottom-

Code:

while((ch=fgetc(fp1)) != EOF)

Finally, you need to close your second file after your while loop-

Code:

fclose(fpo);

[insert]

Code:

	

		

			

			
				
At any rate, one can use something like this to replace gets().

#include <string.h>

char * safegets(char * buffer, size_t count)
{
    char * result = buffer;
    char * tail;
    if(buffer == NULL || count <= 0) 
        result = NULL;
    else if(count == 1)
        *result = '\0';
    else if(fgets(buffer, count, stdin) != NULL) {
        if( (tail = strchr(buffer, '\n')) != NULL)
            *tail = '\0';
    }
    return result;
}

Note the return value of fgets() is checked. If fgets() returns NULL, it failed to read any input from stdin. This usually only happens if the user types End-Of-File, CTRL-Z on DOS and CTRL-D on UNIX, or the input was a file and the end of that file has been reached. Usually this can be ignored, but this function returns NULL if fgets() failed, just in case the caller wants to check it.

As a side note, size_t is the proper type for the lengths of strings.

Use fgets(), not gets(). 

			
		
	

In the wiki page it says size_t is the proper type for the lengths of the strings. I didnt get what it means by that. Is it some identifier in c which is predefined to hold the lengths of the strings?