求一能将小写字母字符串变大的程序C++

刚刚写了一个
#include<iostream>
#include <string.h>
using namespace std;
char toBig (char c);
int main()
{
char arraychar[51];
cout<<"Please int put the chars:(<=50)"<<endl;
cin>>arraychar;

for(int i=0;i<strlen(arraychar);i++)
{
cout<<toBig(arraychar[i]);
}
cout<<endl;

return 0;
}
char toBig(char c)
{
if(c>='a'&& c<='z')
return c+'A'-'a';
return c;
}

好像是按Caps lock

#include<iostream>
using namespace std;
void ToUpper(char*);
int main()
{
char str[]="I am a Chinese!";
ToUpper(str);
cout<<str<<endl;
return 0;
}
void ToUpper(char* str)
{
int i=0;
while(str[i]!='\0')
{
if(str[i]>='a'&&str[i]<='z')