Linux系统下关于函数itoa()?

Question

我编写了个回文数的程序：#include <stdio.h>#include <stdlib.h>#include <string.h>int main(){int i, j;int m, n;int f = 1;char c[10];for (i=1; i<257; i++){m = i * i;itoa(m, c, 10);n = strlen(c);for (j=0; j<n/2; j++){if (c[j] != c[n-1-j]){f = 0;break;}}if (f){printf ("%d\n", i);}}return 0;}结果编译时提示信息：/tmp/cc4rfntR.o: In function `main':jc.c:(.text+0x44): undefined reference to `itoa'collect2: ld returned 1 exit status请问这是为什么？？请高手指教，小弟不甚感激！！！一楼：为什么会没有itoa这个函数？？？