There are multiple differences. Two crucial ones are: fgets() can read from any open file, but scanf() only reads standard input. fgets() reads ‘a line of text’ from a file; scanf() can be used for that but also handles conversions from string to built in numeric types. Many people will use fgets() to read a … Read more
That would be the following macros from inttypes.h: For printf: PRIdPTR PRIiPTR PRIoPTR PRIuPTR PRIxPTR PRIXPTR For scanf: SCNdPTR SCNiPTR SCNoPTR SCNuPTR SCNxPTR Usage example: uintptr_t p = SOME_VALUE; printf(“Here’s a pointer for you: %” PRIxPTR “\n”, p);
Output is buffered. stdout is line-buffered by default, which means that ‘\n’ is supposed to flush the buffer. Why is it not happening in your case? I don’t know. I need more info about your application/environment. However, you can control buffering with setvbuf(): setvbuf(stdout, NULL, _IOLBF, 0); This will force stdout to be line-buffered. setvbuf(stdout, … Read more
The following line will start reading a number (%d) followed by anything different from tabs or newlines (%[^\t\n]). sscanf(“19 cool kid”, “%d %[^\t\n]”, &age, buffer);
Never use gets. It offers no protections against a buffer overflow vulnerability (that is, you cannot tell it how big the buffer you pass to it is, so it cannot prevent a user from entering a line larger than the buffer and clobbering memory). Avoid using scanf. If not used carefully, it can have the … Read more
For printf, the * allows you to specify the minimum field width through an extra parameter, e.g. printf(“%*d”, 4, 100); specifies a field width of 4. A field width of 4 means that if a number takes less than 4 characters to print, space characters are printed until the field width is filled. If the … Read more
From the standard, 7.21.6.2p10 ((f)scanf, applies to the whole family): … If this object does not have an appropriate type, or if the result of the conversion cannot be represented in the object, the behavior is undefined. Looks like another reason to be very cautious with the scanf family. The strtoXX functions have a fully … Read more
scanf consumes only the input that matches the format string, returning the number of characters consumed. Any character that doesn’t match the format string causes it to stop scanning and leaves the invalid character still in the buffer. As others said, you still need to flush the invalid character out of the buffer before you … Read more
Your array needs to be able to hold four chars, since it must also contain the 0-terminator. With that fixed, specifying a maximal length in the format, scanf(“%3s”, string); ensures that scanf reads no more than 3 characters.
They are declared in <inttypes.h> as macros: SCNd8, SCNd16, SCNd32 and SCNd64. Example (for int32_t): sscanf (line, “Value of integer: %” SCNd32 “\n”, &my_integer); Their format is PRI (for printf)/SCN (for scan) then o, u, x, X d, i for the corresponding specifier then nothing, LEAST, FAST, MAX then the size (obviously there is no … Read more