Thread: Can anyone show me what is wrong here? Segmentation fault

Anyone have any ideas on how to alphabetize by last name the list of names in the file?

I got your code working. Tough assignment for me. (still learning C). Been working on it since noon, about 9-10 hours of work I guess. Thought I'd share.

One of the issues you had was the fscanf() reading the count. It was leaving the CRLF in the input stream, and the first fgets() to read a record read only the CRLF.

Also, your pointers are a level deeper than the need to be.

Code:

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

int read_file(char **first_name[], char **last_name[], char **age[]) {
	int count, i;
	char line[80];
	FILE *fp = fopen("names.txt", "r");
	if (fp==NULL) return 0 ; 
	
	//printf("fp = %08X, *fp = %08X\n", &fp, fp );

	fgets(line, 80, fp); //count = how many names in the file on the first line
	count = atoi(line) ; 
	
	*last_name =  malloc(count * sizeof(char *));
	//printf(" 3 word area for last name pointers starts @ %p\n", *last_name);

	*first_name = malloc(count * sizeof(char *));
	//printf(" 3 word area for first name pointers starts @ %p\n", *first_name);
	
	*age = malloc(count * sizeof(char *));
	//printf(" 3 word area for age pointers starts @ %p\n", *age);

	for (i = 0; i < count; i++) {

		fgets(line, 80, fp);
		(*last_name)[i]  = malloc( 21 * sizeof(last_name) ); // area for last name 
		(*first_name)[i] = malloc( 21 * sizeof(first_name) ); // area for first name 
		(*age)[i]        = malloc(  4 * sizeof(age) ); // area for age 
		strcpy( (*last_name)[i] , strtok(line,", \n") ) ; 
		strcpy( (*first_name)[i], strtok(NULL,", \n") ) ; 
		strcpy( (*age)[i]       , strtok(NULL,", \n") ) ; 
	}
	return count ; 
}

int main() { 
	int i, count ; 
	char **ages, **first_names, **last_names ;
	char **ln, **fn, **age ; 
	
	count = read_file(&first_names, &last_names, &ages);

	ln  = (char **) last_names  ; 
	fn  = (char **) first_names ; 
	age = (char **) ages ; 
		
	for ( i = 0 ; i < count ; i++ ) {

		printf("Lastname=%s, Firstname=%s, Age=%s\n", 
			*ln,  
			*fn , 
			*age ) ; 
			ln  += 1 ; 
			fn  += 1 ; 
			age += 1 ; 
	}

	return 0;
}

I added code at the end to print out the records too. It's really not that much code when it comes down to it.

Todd