sscanf

sscanf is a function in the C standard library that reads formatted input from a string. It is declared in stdio.h and serves as the string-input counterpart to scanf and fscanf. The function parses the input according to a format string and stores the results in variables supplied through additional arguments.

Signature and behavior: int sscanf(const char *str, const char *format, ...); It reads from str, applying the format string to guide conversions. The additional arguments must be pointers to suitably typed variables. The function returns the number of input items successfully matched and assigned; if input fails before any conversion, it returns EOF.

Format and conversions: The format string controls how input is consumed. Whitespace in the format matches any amount of whitespace in the input. Literal characters in the format must match exactly in the string. Conversion specifiers follow the scanf family, such as %d, %f, %s, %c, %x, and %[...]. Field width modifiers (for example %10s) limit how many characters are read, and length modifiers (h, l, ll, L) adjust the target type. A asterisk after the % (e.g., %*d) suppresses assignment for that field. The %[...]-conversion reads a non-empty sequence of characters from a set or its negation.

Examples and cautions: Example: const char *s = "42 hello"; int n; char w[6]; sscanf(s, "%d %5s", &n, w); This yields n = 42 and w = "hello". To avoid buffer overflow, always provide field width limits for string inputs and verify the return value to determine how many items were parsed. As with other input functions, correctness depends on the provided format and input validity.