c - scanf won't terminate with hex values? -

when run code:

main(){      int hex;     printf("enter 4 hex values:\n");     while(scanf("%x", &hex) == 1)     {         body     }  } 

it runs body of code, shows cursor , user can input more data until enter null. how can fix while loop once user enters data, 014c 456b 0894 0011 (some random hex numbers), body , program terminates? i.e., why loop ending when user inputs null , how fix this?

you call scanf() until error or eof (it test number of values — marks that). if want call 4 times, have limit separately:

int main(void) {     int hex;     printf("enter 4 hex values: ");     (int = 0; < 4 && scanf("%x", &hex) == 1; i++)     {         …body…     }     return 0; } 

note use of &hex instead of hex in call scanf(); need pass pointer (but if object array, string, pass name without & in front).

if need detect whether exited before getting 4 values, define i outside loop , test afterwards.

also note explicit return type main(); required current , previous versions of c standard. archaic, quarter-century old first version of standard allowed implicit int. , standard required return value main() modern ones let off hook (more's pity, imo).