【急】编写C函数 就是C函数库里函数的功能.编写C函数：1）字符串连接函数Str…

char* StrCat (char *firstStr, char *secondStr)
{
char* beg = firstStr;
while(*firstStr) ++firstStr;
while(*firstStr++=*secondStr++);
return beg;
}
char* StrCpy (char *firstStr, char *secondStr)
{
char* beg = firstStr;
while(*firstStr++=*secondStr++);
return beg;
}