c - Using while(getchar()!='\n') I empty the stdin, but I have to push on Enter key -

i'm using while(getchar()!='\n') empty stdin, if want go on, need push on enter key , computation continue... why? i'll post part of code:

while(1){    if(fgets(buffer,max_dimension,stdin)==null){ perror("error"); exit(1);}    }else{        printf("not correct term\n");        while(getchar()!='\n');        sleep(1);     } } 

thanks!

@iharob if set max_dimension=1240 , send input: string > 1024 remains on stdin, have use while(getchar()!='\n')

2 issues:

1: code has }.

//                                                                   here if(fgets(buffer,max_dimension,stdin)==null){ perror("error"); exit(1);} }else{ // or @ beginning 

2: assuming above not issue, @unxnut answered, typically fgets() contains '\n' , there no need empty stdin.

yet when line excessively long , '\n' not read fgets(), makes sense read until end found.

  if (fgets(buffer, max_dimension, stdin) == null) {     perror("error");     exit(1);   }   if (strchr(buffer, '\n') == null) {     int ch;     printf("not correct term\n");     while (((ch = getchar()) != '\n') && (ch != eof))       ;     // while(getchar()!='\n');     sleep(1);   }