Put a string in a matrix in C - c

Question

I need to put a string (from a file) in a matrix and print out the result. I have some issue in understanding the right way to do this so:
#include <stdio.h>
#include <string.h>
int main (int argc, char *argv[])
{
const int MAX = 50;
char mat[MAX][MAX];
char str[MAX];
char word[MAX];
int row = 0;
int i = 0;
FILE * fp;
fp = fopen ("file.txt", "r");
if (fp == NULL)
printf ("Error!\n");
while (fgets(str, MAX, fp) != NULL)
{
sscanf (str, "%s\n", word);
strcpy(mat[i][0], word);
row++;
}
for (i = 0; i <= row; i++)
{
puts(mat[i][0]);
}
return 0;
}
I'm obliviously doing something wrong but... what?
I have a file like this:
One
Two
Three
Four
Five
Six
Hello

Answer 1

If you compile this with gcc, it will give you two warnings: each warning points to one of the three major errors in the code:
main.c: In function 'main':
main.c:24: warning: passing argument 1 of 'strcpy' makes pointer from integer without a cast
main.c:31: warning: passing argument 1 of 'puts' makes pointer from integer without a cast
Each of those line numbers -- 24 and 31 -- is a line where you're using mat[i][0], which is a character, when you should instead use mat[i], which is a character array. Fix those, and then there's just one problem: you use i, which is always 0, in the while loop. Use row, which is incremented as the row progresses, and the program should work exactly as designed.
There are a couple of other things I would change to improve the program: your while loop reads a string into one buffer, copies it into a second buffer, then copies it into the matrix; you could just scan it directly into the matrix and be done with it!

Answer 2

A matrix usually contains numbers. Yours contains chars. There are problems with your code but to get a good answer you should tell us the format of the file you are reading (maybe paste a small one in your question).
EDIT:
This file contains an array of strings separated by newline. You can read it like this (if the strings don't have any whitespace in them):
while (fscanf(fp, "%s\n", mat[row]) > 0)
{
row++;
}
for (i = 0; i <= row; i++)
{
printf( "%s\n", mat[i]);
}

Answer 3

You should copy the string to the element of matrix with the given index. You should pass the pointer to the first element of matrix to strcpy(i.e. remove the [0]).
Do something like:
while (fgets(str, MAX, fp) != NULL)
{
sscanf (str, "%s\n", word);
strcpy(mat[i], word);
row++;
}
EDIT: also when printing the strings use only mat[i] not mat[i][0].

Answer 4

I have done some changes to your code. First lets pin point your mistakes.
char mat[MAX][MAX]; will not serves your intention of creating string matrix.
It is unnecessary to do read sscanf (str, "%s\n", word);. Already you read it from file. you can directly use it.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
const int MAX = 50;
char *mat[MAX][MAX];
char str[MAX];
int i = 0, j = 0;
int now = 0;
FILE * fp;
fp = fopen ("file.txt", "r");
if (fp == NULL)
printf ("Error!\n");
while (fgets(str, MAX, fp) != NULL)
{
//sscanf (str, "%s\n", word);
mat[i][j] = malloc(sizeof(str));
strcpy(mat[i][j], str);
j++;
now++; //Tracks no.of elements
if(j == MAX)
{
j = 0;
i++; //store in next row
}
}
for (i = 0; i < MAX; i++)
for (j = 0; j < MAX; j++)
{
if(now == 0)
break;
now--;
puts(mat[i][j]);
free(mat[i][j]);//Avoids memory leak
}
return 0;
}