Segmentation Fault when executing Program that prints out a number input
 

I get a segmentation fault when executing this program

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <iostream>
#include <cstdlib>
#include <string.h>

using namespace std;

int main(int argc, char *argv[])
{
int num, rest, len, result;
int control= 0;
char *str;
bool flag = true;
int multi10 = 1;
if(argc == 2){
len = strlen(argv[1]);
}
for(int i = 0; i == len-1 || isdigit(argv[1][i]) ; i++){
flag = false;
}
if(argc != 2 || flag){
cout << "To many or not enough parameters! Enter a number:";
cin >> num;
while(!isdigit(num)){
cout << "\nEnter a number:";
cin >> num;
}
}
else{
num = atoi(argv[1]);
}
if(num > 9){
result = num;
while(result > 9){

result = result/10;
multi10 = multi10 *10;
}
do{
str[control] = result;
rest = num - multi10 * result;
result = rest;
while(result > 9){
result = result/10;
multi10 = multi10 * 10;
}
control++;
}while(result > 0);
cout << str;
return EXIT_SUCCESS;
}
}

here is one problem..
i would bet that will cause a segfault.. use something else.. like
char str[SOME_SIZE];
str[control] = result;


and also
code tags! :mad: