Dotaz: undefined reference to itoa ()

[xsustek]

Prosim vas, mohol by mi niekto pomoct. Som uply zaciatocnik v C a mam problem ked kompilujem kod. Prekladac mi vypisuje undefined reference to itoa (). Pokilal som dobre pozeral tato funkcia by mala byt sucastou stdlib.h. Takze nechapem co ten linker potrebuje nalinkovat. Ak niekto bude vediet, mozte mi napisat aj ako to nalinkujem. Dakujem.

Odpovědi

[zabza]

funkce itoa() opravdu neexistuje...

[Michal Kubeček]

Na některých platformách asi ano (nejspíš inverze k atoi()), ale ne v POSIXu ani v dalších rozšířeních glibc; tipoval bych, že jde o pokus přeložit program psaný původně pro nějakou jinou platformu. Takhle to dopadá, když se nepoužívá -Wall nebo se ignorují varování překladače.

[ams]

#include <stdio.h>
#include <string.h>

/*
Converts an integer value to a null-terminated string using 
the specified radix and stores the result in the given buffer.
If radix is 10 and value is negative the string is preceded by 
the minus sign (-). With any other radix, value is always considered 
unsigned. buffer should be large enough to contain any possible value: 
(sizeof(int)*8+1) for radix=2, i.e. 17 bytes in 16-bits platforms 
and 33 in 32-bits platforms.
Parameters:
 value    Value to be represented as a string. 
 buffer   Buffer where to store the resulting string. 
 radix    Numeral radix in which value has to be represented, between 2 and 36. 
Return Value:
 A pointer to the string. 
No error checking is performed.
*/
char* itoa (int value, char* buffer, int radix)
{
        if ( radix == 10 ) {
                sprintf (buffer, "%d", value);
        } else {
                char tmp_buffer[ sizeof(int)*8 + 1 ];
                char *ptr = &tmp_buffer[ sizeof(int)*8 ];
                unsigned n = value;
                *ptr-- = 0;
                do {
                        *ptr-- = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" [n % radix];
                        n /= radix;
                } while ( n );
                strcpy (buffer, ++ptr);
        }
}

int main ()
{
        int  value, radix;
        char buffer[sizeof(int)*8 + 1];
        while (1) {
                printf ("Value (decimal): "); scanf ("%d", &value);
                printf ("Radix (2 .. 36): "); scanf ("%d", &radix);
                if ( radix < 2 || radix > 36 ) {
                        printf("Good bye!\n");
                        return 0;
                }
                itoa (value, buffer, radix);
                printf("Result: %s\n", buffer);
        }
}

[ams]

#include <stdio.h>
#include <string.h>

/*
Converts an integer value to a null-terminated string using 
the specified radix and stores the result in the given buffer.
If radix is 10 and value is negative the string is preceded by 
the minus sign (-). With any other radix, value is always considered 
unsigned. buffer should be large enough to contain any possible value: 
(sizeof(int)*8+1) for radix=2, i.e. 17 bytes in 16-bits platforms 
and 33 in 32-bits platforms.
Parameters:
 value    Value to be represented as a string. 
 buffer   Buffer where to store the resulting string. 
 radix    Numeral radix in which value has to be represented, between 2 and 36. 
Return Value:
 A pointer to the string. 
No error checking is performed.
*/
char* itoa (int value, char* buffer, int radix)
{
        if ( radix == 10 ) {
                sprintf (buffer, "%d", value);
        } else {
                char tmp_buffer[ sizeof(int)*8 + 1 ];
                char *ptr = &tmp_buffer[ sizeof(int)*8 ];
                unsigned n = value;
                *ptr-- = 0;
                do {
                        *ptr-- = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" [n % radix];
                        n /= radix;
                } while ( n );
                strcpy (buffer, ++ptr);
        }
}

int main ()
{
        int  value, radix;
        char buffer[sizeof(int)*8 + 1];
        while (1) {
                printf ("Value (decimal): "); scanf ("%d", &value);
                printf ("Radix (2 .. 36): "); scanf ("%d", &radix);
                if ( radix < 2 || radix > 36 ) {
                        printf("Good bye!\n");
                        return 0;
                }
                itoa (value, buffer, radix);
                printf("Result: %s\n", buffer);
        }
}

[ams]

Omlouvam se za 2-krat vlozeny prispevek. Chtel jsem vlozit upravenou verzi programu a nejak mi to odeslalo podruhe. Spravne by na konci funkce itoa melo stat return buffer;. Takze nejak takto:

                } while ( n );
                strcpy (buffer, ++ptr);
        }
        return buffer;
}

[nobody important]

funce itoa() existuje

do hlavičky hezky

#include <stdlib.h>

a pak už jen

itoa(I,S,i)

kde I je vstupní integer; S výstupní string a i je soustava (2-dvojkova;8-osmičková;10-desítková;16-hexadecimální)

[Luboš Doležel (Doli)]

$ grep itoa /usr/include/gentoo-multilib/amd64/stdlib.h
$

?

[Ash]

http://en.wikipedia.org/wiki/Stdlib.h