The printf() family of functions uses % character as a placeholder. When a % is encountered, printf reads the characters following the % to determine what to do: %s – Take the next argument and print it as a string %d – Take the next argument and print it as an int See this Wikipedia … Read more
Here is the original answer from Stack Overflow. As others have mentioned, you need snprintf not sprintf. Make sure the second argument to snprintf is zero. That will prevent snprintf from writing to the NULL string that is the first argument. The second argument is needed because it tells snprintf that enough space is not … Read more
Some here are arguing that this approach is overkill, and for converting ints to strings I might be more inclined to agree. But when a reasonable bound for string size cannot be found, I have seen this approach used and have used it myself. int size = snprintf(NULL, 0, “%d”, 132); char * a = … Read more
The direct answer is that yes, that’s okay. A lot of people have thrown around various ideas of how to improve speed, but there seems to be quite a bit of disagreement over which is most effective. I decided to write a quick test program to get at least some idea of which techniques did … Read more
Don’t pass the results to printf. pass them to vprintf. vprintf specifically exists to handle passing in va_list arguments. From the Linux man page: #include <stdio.h> int printf(const char *format, …); int fprintf(FILE *stream, const char *format, …); int sprintf(char *str, const char *format, …); int snprintf(char *str, size_t size, const char *format, …); #include … Read more
printf(“%f + i%f\n”, creal(result), cimag(result)); I don’t believe there’s a specific format specifier for the C99 complex type.
You can use the [n] notation to specify explicit argument indexes like so: fmt.Printf(“%[1]d %[1]d\n”, i) Here is a full example you can experiment with: http://play.golang.org/p/Sfaai-XgzN
You can use the same ll size modifier for %x, thus: #include <stdio.h> int main() { unsigned long long x = 123456789012345ULL; printf(“%llx\n”, x); return 0; } The full range of conversion and formatting specifiers is in a great table here: printf documentation on cppeference.com
There is no need to construct a special format string. printf allows you to specify the precision using a parameter (that precedes the value) if you use a .* as the precision in the format tag. For example: printf (“%d %.*s”, number, SIZE, letters); Note: there is a distinction between width (which is a minimum … Read more
From http://pubs.opengroup.org/onlinepubs/009695399/functions/printf.html: z Specifies that a following […] conversion specifier applies to a size_t or the corresponding signed integer type argument; t Specifies that a following […] conversion specifier applies to a ptrdiff_t or the corresponding unsigned type argument; And from http://en.wikipedia.org/wiki/Size_t#Size_and_pointer_difference_types: size_t is used to represent the size of any object (including arrays) in … Read more