请教一个简单的C题目 - C/C++ / C语言

C/C++ code:
#include <stdio.h>
#include <string.h>
void main()
{
int i,iLength=0,tLength=0;
char s[]="I AM A STUDENT";
char t[]="GOOD";
while(s[iLength]!='\0')
iLength++;
{
for(i=0;i<iLength;i++)
printf("%c",s[i]);
printf("\nStrLenth(s)=%d\n",iLength);
}
while(t[tLength]!='\0')
tLength++;
{
for(i=0;i<tLength;i++)
printf("%c",t[i]);
printf("\nStrLenth(t)=%d\n",tLength);
}
}

题目是s="I AM A STUDENT",t="GOOD",求StrLenth(s)、StrLenth(t) (字符串的长度)
上面是我写的，我想用调用函数来做，怎么实现它？各位帮帮忙。

---

C/C++ code:

int StrLenth(char *str)
{
if (str == NULL) return 0;
int strLength = 0;
while(str[strLength] != '\0')
{
strLength++;
}
return strLength;
}

---

如果想封装成函数的话，楼主可以参考一下strlen的原型：
http://baike.baidu.com/view/736226.htm

---

谢谢大家帮忙

---

#include <stdio.h>
#include <string.h>
int strleght(char* str)
{
int i = 0;
while(str[i] != '\0')
{
i ++;
}
str[i] = '\0';
return i;
}
void main()
{
int i = 0,iLength=0,tLe