parse integer without appending char in C
c, scanf
Solution
For your problem, you can use `strtol()` function from the `#include <stdlib.h>` library.
How to use `strtol`(Sample code from tutorial points)
#include <stdio.h>
#include <stdlib.h>
int main(){
char str[30] = "2030300 This is test";
char *ptr;
long ret;
ret = strtol(str, &ptr, 10);
printf("The number(unsigned long integer) is %ld\n", ret);
printf("String part is |%s|", ptr);
return(0);
}
Inside the `strtol`, it scans `str`, stores the words in a pointer, then the base of the number being converted. If the base is between 2 and 36, it is used as the radix of the number. But I recommend putting zero where the 10 is so it will automatically pick the right number. The rest is stored in `ret`.
Problem
I want to parse an integer but my following code also accepts Strings like "3b" which start as a number but have appended chars. How do I reject such Strings? ``` #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { int n; if(argc==2 && sscanf(argv[1], "%d", &n)==1 && n>0){ f(n); return 0; } else{ exit(EXIT_FAILURE); } } ```