程序如下：
#include <iostream>

void main()
{    char a[]="abcdefghijklmnopqrstuvwxyz";
    int i;
    for(i=0;i<25;i++)
    {   
        std::cout<<"\'"<<a[i]<<"\'"
            <<"="<<int(a[i])
            <<"="<<oct(a[i])
            <<"="<<hex(a[i]);
    }
}
显示找不到标识符oct和hex。

hex和oct不是标准库函数也不是关键字吧

#include <iostream>

int main()
{
    const char* str = "abcdefghijklmnopqrstuvwxyz";
    const size_t len = strlen(str);

    for( size_t i=0; i<len; ++i )
    {  

        std::cout << '\'' << str[i] << '\''
                  << '=' << std::dec << int(str[i])
                  << '=' << std::oct << int(str[i])
                  << '=' << std::hex << int(str[i]) << '\n';
    }

    return 0;
}