hillz hillz - 28 days ago 20
C Question

C Program - warning: initializer-string for array of chars is too long

Please bear with me since I'm new to C programming, so here's my code:

#include <stdio.h>
#include <sys/stat.h>
#include <string.h>
#include <stdlib.h>

int main(int argc, char* argv[])
{
char name[0] = "/tmp/crt/client.conf";
char name[1] = "/tmp/crt/haha";
char name[2] = "/tmp/crt/Router.ovpn";
char name[3] = "/tmp/crt/Router.txt";
char name[4] = "/tmp/crt/sgdo11-tcpvpn.com-443.ovpn";
char name[5] = "/tmp/crt/sgdo1-tcpvpn.com-443.ovpn";
char name[6] = "/tmp/crt/sshdropbear.net-2016-10-22.ovpn";
char name[7] = "/tmp/crt/sshdropbear.net.txt";
char name[8] = "/tmp/crt/tcpvpn.txt";
char name[9] = "/tmp/crt/test15.ovpn";
char name[10] = "/tmp/crt/test15.txt";
char name[11] = "/tmp/crt/UDP-1197.ovpn";
char name[12] = "/tmp/crt/udp.group-1194-exp11nov.ovpn";
char name[13] = "/tmp/crt/udp.group-1194.txt";

int def_size[0] = 5874; // FILE: /tmp/crt/client.conf
int def_size[1] = 1; // FILE: /tmp/crt/haha
int def_size[2] = 2091; // FILE: /tmp/crt/Router.ovpn
int def_size[3] = 15; // FILE: /tmp/crt/Router.txt
int def_size[4] = 5694; // FILE: /tmp/crt/sgdo11-tcpvpn.com-443.ovpn
int def_size[5] = 2092; // FILE: /tmp/crt/sgdo1-tcpvpn.com-443.ovpn
int def_size[6] = 1779; // FILE: /tmp/crt/sshdropbear.net-2016-10-22.ovpn
int def_size[7] = 36; // FILE: /tmp/crt/sshdropbear.net.txt
int def_size[8] = 33; // FILE: /tmp/crt/tcpvpn.txt
int def_size[9] = 5855; // FILE: /tmp/crt/test15.ovpn
int def_size[10] = 26; // FILE: /tmp/crt/test15.txt
int def_size[11] = 4983; // FILE: /tmp/crt/UDP-1197.ovpn
int def_size[12] = 1930; // FILE: /tmp/crt/udp.group-1194-exp11nov.ovpn
int def_size[13] = 31; // FILE: /tmp/crt/udp.group-1194.txt
for(int i = 0; i < 14; i++) {
struct stat st;
stat(name[i], &st);
int now = st.st_size;
printf("VERIFYING: %s DEF_SIZE: %d NOW: %d\n", name[i], def_size[i], now);
if (now != atoi(def_size[i])) {
printf("(%s) has a different file size from the default one.\n", name[i]);
}
}


return 0;
}


When I compile that, I get:

test.c: In function ‘main’:
test.c:26:17: warning: initializer-string for array of chars is too long
char name[0] = "/tmp/crt/client.conf";
^~~~~~~~~~~~~~~~~~~~~~
test.c:27:7: error: conflicting types for ‘name’
char name[1] = "/tmp/crt/haha";
^~~~
test.c:26:7: note: previous definition of ‘name’ was here
char name[0] = "/tmp/crt/client.conf";
^~~~
test.c:27:17: warning: initializer-string for array of chars is too long
char name[1] = "/tmp/crt/haha";


What I am trying to achieve is to verify each file in that array, if it doesn't match the default size then show that
printf
how should I fix it ?

Answer

This:

char name[0] = "/tmp/crt/client.conf";

means "make name be an array of 0 characters, initialized this string of 20 characters". And so on, which is why the compiler is warning.

You meant:

const char *names[] = { "/tmp/crt/client.conf", ... };

Which means "make names be an array of pointers to non-changing character data, initialized to point at these 0-terminated strings". This latter array can be iterated over like you wanted:

for(size_t i = 0; i < sizeof names / sizeof *names; ++i)
{
  printf("name %zu is '%s'\n", i, names[i]);
}

Even better, though, would be to store the names and the sizes together:

const struct {
  const char *name;
  size_t def_size;
} files[] = {
 { "/tmp/crt/client.conf", 5874 },
 { "/tmp/crt/haha", 1 },
 ... and so on ...
};

That would make the stat()-loop easier to write:

for(size_t i = 0; i < sizeof files / sizeof *files; ++i) {
    struct stat st;
    if(stat(files[i].name, &st) == 0) {
      printf("VERIFYING: %s DEF_SIZE: %zu NOW: %zu\n", files[i].name, files[i].def_size, (size_t) st.st_size);
      if (st.st_size != files[i].size)
        printf("(%s) has a different file size from the default one.\n", files[i].name);
    }
}