printf(fmt [, val, ...]) - converts, formats, and writes its val parameters, under control of fmt, to stdout.

scanf(fmt [, ptr, ...]) - reads string from stdin, converts it according to fmt, and stores result at memory location ptr.

fscanf(stream, fmt [, ptr, ...]) - reads string from stream, converts it according to fmt, and stores result at memory location ptr.

sscanf(s, fmt [, ptr, ...]) - reads string from memory location at s, converts it according to fmt, and stores result at memory location ptr.

sprintf(s, fmt [, val, ...]) - converts, formats, and stores its val parameters, under control of fmt, into consecutive bytes starting at s. A null terminator is added.

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Most other functions can be found in the appropriate section(s) of this document.