Man: View library function syntax and header file

Every time I want to query the file of a C-library function, I always search for it online and then see it in my blog. You have to read several articles before you can find them.

This is not a solution. Windows has msdn and Linux has man. Why not use it?

1. Check man's Manual description. Man is a verb, a noun, or an adjective)

$ Man

       The table below shows the section numbers of the manual followed by the types of pages they contain.       1   Executable programs or shell commands       2   System calls (functions provided by the kernel)       3   Library calls (functions within program libraries)       4   Special files (usually found in /dev)       5   File formats and conventions eg /etc/passwd       6   Games       7   Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7)       8   System administration commands (usually only for root)       9   Kernel routines [Non standard]

As you can see, the fourth is the library function manual.

2. view the printf header file

$ MAN 3 printf

View format specifiers and search for specifier

   The conversion specifier       A character that specifies the type of conversion to be applied.  The conversion specifiers and their meanings are:       d, i   The  int  argument is converted to signed decimal notation.  The precision, if any, gives the minimum number of digits that must appear; if the converted value              requires fewer digits, it is padded on the left with zeros.  The default precision is 1.  When 0 is printed with an explicit precision 0, the output is empty.       o, u, x, X              The unsigned int argument is converted to unsigned octal (o), unsigned decimal (u), or unsigned hexadecimal (x and X) notation.  The letters  abcdef  are  used              for x conversions; the letters ABCDEF are used for X conversions.  The precision, if any, gives the minimum number of digits that must appear; if the converted              value requires fewer digits, it is padded on the left with zeros.  The default precision is 1.  When 0 is printed with an explicit precision 0, the  output  is              empty.

View the header file.

PRINTF(3)                                                                 Linux Programmer's Manual                                                                 PRINTF(3)NAME       printf, fprintf, sprintf, snprintf, vprintf, vfprintf, vsprintf, vsnprintf - formatted output conversionSYNOPSIS       #include <stdio.h>       int printf(const char *format, ...);       int fprintf(FILE *stream, const char *format, ...);

If direct:

$ Man printf

The default display is 1st: executable programs or shell commands.

1 executable programs or shell commands