Write function:
#include<stdlib.h>
int StringToInt(char *str)
{
char c;
int i,digit=0;
int k=1;
for(i=strlen(str);i>0;i--)
{
digit+=(str-'0')*k;
k*=10;
};
return digit;
}
This function convert String to unsigned Integer. WARNING this function not check input argument