The scanf() function skips leading whitespace automatically before trying to parse conversions other than characters. The character formats (primarily %c; also scan sets %[…] — and %n) are the exception; they don’t skip whitespace. Use ” %c” with a leading blank to skip optional white space. Do not use a trailing blank in a scanf() … Read more
The %c conversion specifier won’t automatically skip any leading whitespace, so if there’s a stray newline in the input stream (from a previous entry, for example) the scanf call will consume it immediately. One way around the problem is to put a blank space before the conversion specifier in the format string: scanf(” %c”, &c); … Read more
The most common ways of reading input are: using fgets with a fixed size, which is what is usually suggested, and using fgetc, which may be useful if you’re only reading a single char. To convert the input, there are a variety of functions that you can use: strtoll, to convert a string into an … Read more
Try using the “%h” modifier: scanf(“%hu”, &length); ^ ISO/IEC 9899:201x – 7.21.6.1-7 Specifies that a following d , i , o , u , x , X , or n conversion specifier applies to an argument with type pointer to short or unsigned short.
An array “decays” into a pointer to its first element, so scanf(“%s”, string) is equivalent to scanf(“%s”, &string[0]). On the other hand, scanf(“%s”, &string) passes a pointer-to-char[256], but it points to the same place. Then scanf, when processing the tail of its argument list, will try to pull out a char *. That’s the Right … Read more
People (and especially beginners) should never use scanf(“%s”) or gets() or any other functions that do not have buffer overflow protection, unless you know for certain that the input will always be of a specific format (and perhaps not even then). Remember than scanf stands for “scan formatted” and there’s precious little less formatted than … Read more
Because C will promote floats to doubles for functions that take variable arguments. Pointers aren’t promoted to anything, so you should be using %lf, %lg or %le (or %la in C99) to read in doubles.
They are the same when used for output, e.g. with printf. However, these are different when used as input specifier e.g. with scanf, where %d scans an integer as a signed decimal number, but %i defaults to decimal but also allows hexadecimal (if preceded by 0x) and octal (if preceded by 0). So 033 would … Read more