ITOA and sprintf functions Linux C string processing functions

ITOA and sprintf functions Linux C string processing functions

 ITOA functions and atoi functions,C LanguageProvides several standard library functions to convert numbers of any type (integer, long integer, floating point type, etc.) to characters

String. Here is an example of converting integers into strings using the ITOA () function:

# Include  <  Stdio. h  >  
# Include  <  Stdlib. h  >  

  Void  Main (  Void  )
{
  Int Num  =     100  ;
  Char  STR [  25  ];
ITOA (Num, STR,  10  );
Printf (  "  The number 'num' is % d and the string 'str' is % S./n  "  ,
Num, STR );
}

The ITOA () function has three parameters: the first parameter is the number to be converted, the second parameter is the target string to write the conversion result, and the third parameter is used when the number is transferred.

. In the preceding example, the conversion base is 10. 10  : Decimal;  2  : Binary...

ITOA is not a standard C function, it is unique to Windows, if you want to write cross-platformProgram, Use sprintf.
It is extended on the Windows platform. The standard library contains sprintf, which is more powerful than this one. Its usage is similar to that of printf:

  Char  STR [  255  ];
Sprintf (STR,  "  % X  "  ,  100  );  // Convert 100 to a hexadecimal string.  
  
The following functions can convert integers into strings:
  ----------------------------------------------------------  
Function Name
  ----------------------------------------------------------  
ITOA () converts an integer value to a string
Ltoa () converts a long integer value to a string
Ultoa () converts an unsigned long integer value to a string


A atoi converts a string to an integer.

Example program:

# Include  <  Ctype. h  >  
# Include  < Stdio. h  >  
  Int  Atoi (  Char  S []);

  Int  Main (  Void  )
{

  Char  S [  100  ];

Gets (s );

Printf (  "  Integer = % d/n "  , Atoi (s ));
  Return     0  ;
}
  Int  Atoi (  Char  S [])
{
  Int  I, n, sign;

  For  (I  =  0  ; Isspace (s [I]); I ++  )  //  Skip blank characters  
  ;
Sign  =  (S [I]  =  '  -  '  )  ? -  1  :  1  ;
 If  (S [I]  =  '  +  '  |  S [I]  =  '  -  '  )  //  Skip symbol  
  I  ++ ;
  For  (N  =  0  ; Isdigit (s [I]); I  ++  )
N  =  10  *  N  +  (S [I]  -  '  0  ' );  //  Convert numeric characters into integer characters  
  Return  Sign  *  N;

}

ITOA converts an integer to a string.

Example program:

# Include  <  Ctype. h  >  
# Include  <  Stdio. h  >  
 Void  ITOA (  Int  N,  Char  S []);
  //  Atoi function: Convert s to integer  
  Int  Main (  Void  )
{
  Int  N;
  Char  S [ 100  ];

Printf (  "  Input N:/n  "  );
Scanf (  "  % D  "  ,  &  N );

Printf (  "  The string:/n  "  );
ITOA (N, S );
 Return     0  ;
}
  Void  ITOA (  Int  N,  Char  S [])
{
  Int  I, j, sign;

  If  (Sign  =  N)  < 0  )  //  Record symbols  
  N  =-  N;  //  Make n a positive number  
  I  =  0  ;
  Do  {
S [I  ++ ]  =  N  %  10  +  '  0  '  ;  //  Next Digit  
  }  While  (N  /=  10 )  >  0  );  //  Delete this number  
  
  If  (Sign  <  0  )
S [I  ++  ]  =  '  - '  ;
S [I]  =  '  /0  '  ;
  For  (J  =  I; j  > =  0  ; J  --  )  //  The generated number is in reverse order, so it must be output in reverse order. 
  Printf (  "  % C  "  , S [J]);

}