Category : C Source Code
Archive   : CSRC2.ZIP
Filename : ITOA.C

 
Output of file : ITOA.C contained in archive : CSRC2.ZIP
/*
* i t o a . c
*/

/*)LIBRARY
*/

#ifdef DOCUMENTATION

title itoa Convert signed integer to Ascii
index Convert signed integer to Ascii

synopsis
.s.nf
char *
itoa(buffer, value)
char *buffer; /* Where result goes */
int value; /* Value to convert */
.s.f
description

itoa() converts a signed integer to its decimal Ascii
representation, storing it in buffer. Buffer will
be null-terminated. Itoa() returns a pointer to
the null-terminator.

Itoa() uses a division table, avoiding hardware division
instructions and recursion. This makes it suitable as a
model for implementation on small machines.

Author

Martin Minow

Implementation

You should #define INT_32 if integers occupy 32 bits.

#endif

/*
* Note: the largest positive 32 bit int is 2,147,483,647
* the largest positive 16 bit int is 32,767
*/

#define FALSE 0
#define TRUE 1
#define EOS 0

static int power10[] = {
#ifdef INT_32
10000000,
1000000,
100000,
#endif
10000,
1000,
100,
10
};

#define NPOWERS ((sizeof power10) / (sizeof (unsigned int)))


static
itoa(value, buffer)
register int value;
register char *buffer;
/*
* Convert an unsigned number to ASCII
*/
{
register unsigned int *power;
int nonzero;

if (value < 0) {
*buffer++ = '-';
value = -value;
}
power = power10; /* Pointer to power table */
nonzero = FALSE; /* Don't output leading zeros */
do {
for (*buffer = '0'; ((unsigned) value) >= *power; *buffer += 1)
value -= *power;
if (*buffer != '0' || nonzero) {
buffer++;
nonzero = TRUE;
}
} while (++power < &power10[NPOWERS]);
*buffer++ = (value + '0'); /* Digits place */
*buffer = EOS;
return (buffer);
}


  3 Responses to “Category : C Source Code
Archive   : CSRC2.ZIP
Filename : ITOA.C

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