用 C 将一个字节写入文件

Question

I have a byte declared as unsigned int 0b11010101 how can I write this to a binary file as 1 byte? I know fwrite takes type const void * as a buffer but I don't know how to write my byte if it's represented as an unsigned int.

Answer 1

Perhaps like this, you better not write one byte of an int because of endianness. Convert to unsigned char first.

unsigned int intval = 0b11010101;       // assuming compiler likes it
unsigned char charval = intval;
fwrite (&charval, 1, 1, stream);

Answer 2

You can write a single byte to a file using fputc() .

Example:

unsigned int val = 0b11010101;
fputc(val, stream);

Tested using:

~ $ cc -Wall -o test test.c
~ $ ./test | xxd
00000000: d5                                       .