问多打印不工作错误6

EN

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char* valueOfParam (char *param) {
//some code but in this case result is null
    return NULL;
}

int main () {
//....
char *vm_title = valueOfParam("title"); 
unsigned int vm_vc; 
if (valueOfParam("vc"))
vm_vc = atoi(valueOfParam("vc"));           
unsigned int vm_dc; 
if (valueOfParam("dc"))
vm_dc  = atoi(valueOfParam("dc"));
unsigned int vm_cl; 
if (valueOfParam("cl"))
vm_cl = atoi(valueOfParam("cl"));
unsigned int vm_pl; 
if (valueOfParam("pl"))
vm_pl = atoi(valueOfParam("pl"));
//.....
printf("vm_title=%s \n<br>", vm_title);
printf("vm_vc=%d \n<br>", vm_vc);
printf("vm_dc=%d \n<br>", vm_dc);
printf("vm_cl=%d \n<br>", vm_cl);
//.....
}

segfault, error 6 in /var/log/messages.

unsigned int vm_users;                              
if (valueOfParam("users")){
    printf("==%s", vm_users);
    //vm_users  = atoi(valueOfParam("users"));
}

vm_users  = atoi(valueOfParam("users"));