ktv有偿陪侍 治安处罚:C语言关于CHAR类型的转换

我这样写：
#include<stdio.h>
#include<stdlib.h>
void pricha(int num2)//这个是我写的方法，没有粘MAIN函数
{
int i;
char c;
switch(num2)
{
case 10:
c='a';
break;
case 11:
c='b';
break;
case 12:
c='c';
break;
case 13:
c='d';
break;
case 14:
c='e';
break;
case 15:
c='f';
break;
case 16:
c='g';
break;
case 17:
c='h';
break;
case 18:
c='i';
break;
case 19:
c='j';
break;
case 20:
c='k';
break;
case 21:
c='l';
break;
case 22:
c='m';
break;
case 23:
c='n';
break;
case 24:
c='o';
break;
case 25:
c='p';
break;
case 26:
c='q';
break;
case 27:
c='r';
break;
case 28:
c='s';
break;
case 29:
c='t';
break;
case 30:
c='u';
break;
case 31:
c='v';
break;
case 32:
c='w';
break;
case 33:
c='x';
break;
case 34:
c='y';
break;
case 35:
c='z';
break;
default:
itoa(num2,c,10);
}
----------------------------
报的错误信息：
D:\a.c(117) : warning C4047: 'function' : 'char *' differs in levels of indirection from 'char '
D:\a.c(117) : warning C4024: 'itoa' : different types for formal and actual parameter 2
D:\a.c(117) : warning C4700: local variable 'c' used without having been initialized
我只想转换一个一位的数字，用一个CHAR就可以不用字符串可以做到吗？