Objective

Implement a tiny printf that walks a format string, expands the conversions %c, %s, %d, %x and %%, writes everything to standard output, and returns the exact number of bytes written.

Steps

• Use the stdarg.h macros to read the variadic arguments: va_start before the first va_arg, va_end at the end.
• Support exactly five conversions: %c (a single character), %s (a string), %d (a signed decimal integer), %x (an unsigned lowercase hexadecimal integer), and %% (a literal percent sign).
• %c is passed through default argument promotion, so read it with va_arg(ap, int) and write the low byte.
• %d must handle negatives and 0; %x is unsigned, so 255 prints as ff and there is no minus sign.
• For %s, a NULL pointer must print the literal text (null).
• For any other character after a %, print the % and that character literally (so %q stays %q).
• Return value: the count must equal the exact number of bytes you wrote, after every conversion has been expanded, not the length of the format string.

Objective

Implement a tiny printf that walks a format string, expands the conversions %c, %s, %d, %x and %%, writes everything to standard output, and returns the exact number of bytes written.

Steps

• Use the stdarg.h macros to read the variadic arguments: va_start before the first va_arg, va_end at the end.
• Support exactly five conversions: %c (a single character), %s (a string), %d (a signed decimal integer), %x (an unsigned lowercase hexadecimal integer), and %% (a literal percent sign).
• %c is passed through default argument promotion, so read it with va_arg(ap, int) and write the low byte.
• %d must handle negatives and 0; %x is unsigned, so 255 prints as ff and there is no minus sign.
• For %s, a NULL pointer must print the literal text (null).
• For any other character after a %, print the % and that character literally (so %q stays %q).
• Return value: the count must equal the exact number of bytes you wrote, after every conversion has been expanded, not the length of the format string.