8. Write a function that takes in a string parameter and checks to see whether or not it is an integer, and if it is then return the integer value.
#include <stdio.h>
int strtoint(char *s)
{
int index = 0, flag = 0;
while( *(s+index) != '\0')
{
if( (*(s + index) >= '0') && *(s + index) <= '9')
{
flag = 1; index++;
}
else
{
flag = 0;
break;
}
}
if( flag == 1 ) return atoi(s);
else return 0;
}
main()
{
printf("%d",strtoint("0123")); printf("\n%d",strtoint("0123ii"));
}