asked on

variable-length array?

What's wrong with this short program, and how do I make it work? (I do not want to fix/limit the size of the array to 10000.)

Thanks.
---------------
#include <stdio.h>
#include <stdlib.h>

void main(int argc, char** argv){
// char content[10000];
if(argc<3){
printf("Usage: \n sendfile number_of_bytes file_name\n");
exit(0);
}

FILE* fout=fopen(argv[2],"w");
int num=atoi(argv[1]);
int * size=(int *)malloc((size_t)num);
char content[*size];
for(int i=0; i<num; i++)content[i]='a';
fwrite(content,1,num,fout);
free(size);
}

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pagladasu

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thienpnguyen

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

void main(int argc, char **argv)
{
// char content[10000];
if(argc < 3)
{
printf("Usage: \n sendfile number_of_bytes file_name\n");
exit(0);
}
FILE * fout = fopen(argv[2], "w");

if( fout == NULL )
return;

int num = atoi(argv[1]);
char *content = (char *)malloc(num*sizeof(int));

if( content == NULL )
return;

for(int i = 0; i < num; i++)
content[i] = 'a';
fwrite(content, 1, num, fout);

free(content);
fclose(fout);
}

thienpnguyen

if you write in "pure" C, the code as following.

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

void main(int argc, char **argv)
{
FILE * fout;
int num, i;
char *content;

// char content[10000];
if(argc < 3)
{
printf("Usage: \n sendfile number_of_bytes file_name\n");
exit(0);
}

fout = fopen(argv[2], "w");
if( fout == NULL )
return;

num = atoi(argv[1]);
content = (char *)malloc(num*sizeof(int));

if( content == NULL )
return;

for(i = 0; i < num; i++)
content[i] = 'a';
fwrite(content, 1, num, fout);

free(content);
fclose(fout);
}

anothercto

ASKER

thienpnguyen,

I'll post 50 points for you.
Thanks.