#include<cstring>
using namespace std;
int main() {
	char a[10];
	gets(a);
	long h=strlen(a);
	int ans=0;
	for(int i=0; i<h; i++) {
		if(a[i]>='A'&&a[i]<='Z')
			ans++;
		if(a[i]>='a'&&a[i]<='z')
			ans++;
		if(a[i]>='0'&&a[i]<='9')
			ans++;
	}
	cout<<ans;
	return 0;
}

编译错误： /tmp/compiler_lsrqk2as/src: 在函数‘int main()’中: /tmp/compiler_lsrqk2as/src:7:2: 错误：‘gets’ was not declared in this scope; did you mean ‘fgets’? 7 | gets(a); | ^~~~ | fgets