C - how to handle user input in a while loop -

C - how to handle user input in a while loop -

i'm new c , have simple programme takes user input within while loop, , quits if user presses 'q':

while(1) { printf("please come in choice: \n1)quit\n2)something"); *choice = getc(stdin); // actions. if (*choice == 'q') break; if (*choice == '2') printf("hi\n"); }

when run , nail 'q', programme quit correctly. if press '2' programme first prints out "hi" (as should) goes on print prompt "please take option" twice. if come in n characters , press enter, prompt gets printed n times.

this same behaviour happens when utilize fgets() limit of 2.

how loop working properly? should take first character of input , 1 time according entered.

edit

so using fgets() larger buffer works, , stops repeated prompt issue:

fgets(choice, 80, stdin);

this kind of helped: how clear input buffer in c?

when getc input, it's of import note user has set in more 1 character: @ least, stdin contains 2 chars:

2\n

when getc gets "2" user has set in, trailing \n character still in buffer, you'll have clear it. simplest way here add together this:

if (*choice == '2') puts("hi"); while (*choice != '\n' && *choice != eof)//eof in case *choice = getc(stdin);

that should prepare it

for completeness: note getc returns int, not char. create sure compile -wall -pedantic flags, , check homecoming type of functions use.

it tempting clear input buffer using fflush(stdin);, , on systems, work. however: this behavior undefined: standard states fflush meant used on update/output buffers, not input buffers:

c11 7.21.5.2 fflush function, fflush works output/update stream, not input stream

however, implementations (for illustration microsoft) back upwards fflush(stdin); extension. relying on it, though, goes against philosophy behind c. c meant portable, , sticking standard, assured code portable. relying on specific extension takes away advantage.

c