char str1[] = "124z3yu87" ;
char str2[] = "1000";
char *str3 = "100";
printf("str1: %d\n", atoi(str1));
printf("str2: %d\n", atoi(str2));
printf("str3: %d\n", atoi(str3));

str1: 124
str2: 1000
str3: 0

why str3 is giving 0