为什么这个C ++程序不能编译？

Question

这是我正在尝试编译的程序。

#include <iostream>
#include <string>
#include <vector>
#include <unistd.h>
using namespace std;

vector<string> paramlist;
const char *programname = "abc";

const char **args = new const char* [paramlist.size()+2];   // extra room for program name and sentinel
args [0] = programname;         // by convention, args[0] is program name
for (int j = 0;  j < paramlist.size()+1;  ++j)     // copy args
args [j+1] = paramlist[j] .c_str();

args [paramlist.size()+1] = NULL;  // end of arguments sentinel is NULL

execv (programname, (char **)args);

当我尝试编译它时，我收到以下错误消息：

test.cpp:11: error: expected constructor, destructor, or type conversion before ‘=’ token
test.cpp:12: error: expected unqualified-id before ‘for’
test.cpp:12: error: expected constructor, destructor, or type conversion before ‘<’ token
test.cpp:12: error: expected unqualified-id before ‘++’ token
test.cpp:15: error: array bound is not an integer constant
test.cpp:15: error: expected constructor, destructor, or type conversion before ‘=’ token
test.cpp:17: error: expected constructor, destructor, or type conversion before ‘(’ token

Answer 1

您至少需要一个int main function。

Answer 2

您的程序包含代码但需要包含在函数中。尝试使用using namespace std;之类的函数在int main行之后包装所有代码。 Google可以查看任何“Hello world”C ++示例。