How to create matrix, by reading the length in an input file

Asked Mar 21 '15 at 10:55

Active Mar 21 '15 at 11:54

Viewed 61 times

I am trying to create a matrix, int matrix1[size][size], but I have to read the length from the first line of a file.

I can read read from the file with no problem, but then when I try to declare the matrix with the variable given to me by the file there's always a compiling error.

How can I get around this?

Sorry about the English

Edited Code:

int num;

FILE *fp;

fp = argc > 1 ? fopen(argv[1], "r") : stdin;
if( fp == NULL) {
    perror(argv[1]); 
    return -1;
}

fscanf(fp,"%d", &num);

int matriz[num][num];

Error message is warning: ISO C90 forbids variable length array ‘matriz’

edited Mar 21 '15 at 11:54

Ed Heal

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asked Mar 21 '15 at 10:55

Alexbot11

can you change(or add) compile option to `-std=c99`? – BLUEPIXY Mar 21 '15 at 12:04
Tried [`malloc()`](http://www.manpagez.com/man/3/malloc/) yet ? – Arun A S Mar 21 '15 at 12:47
@Alexbot11 If it is not C99 or later can not be such a description. You need to be implemented using malloc. – BLUEPIXY Mar 21 '15 at 13:00
i dont have a lot of experience with malloc(); but i guess its time to learn it, since it does seem to be the only way, thank you for the anwsers – Alexbot11 Mar 21 '15 at 13:28
Refer http://stackoverflow.com/questions/1970698/using-malloc-for-allocation-of-multi-dimensional-arrays-with-different-row-lengt – Sorcrer Mar 21 '15 at 15:23

How to create matrix, by reading the length in an input file

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