c - The "EOF" value in different type (an union)? -


i reading c book k&r. know the macro eof on system -1. 

int eof = eof; printf("eof on system is: %d\n",eof);

but when assign eof union, output somehow confused me. can understand v.ival -1. can explain why rest of them: v.cval, v.fval, , v.dval this?

union eof_val {     int ival;     char cval;     float fval;     double dval; } eof;  eof.ival = eof;  printf("eof int = %d\n", eof.ival);        /* output: -1 */ printf("eof char = %c\n", eof.cval);       /* output: � */ printf("eof float = %f\n", eof.fval);      /* output: nan */ printf("eof double = %f\n", eof.dval);     /* output: 0.000000 */

a union big enough hold biggest of it's members. not how them all. 1 of it's values usable @ time.

you've set ival , it's good, means cval, fval , dval pretty hold rubbish (not quite: figure out based on value of ival)

not duplicate, interesting reading: why need c unions?


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