小编Spa*_*Fly的帖子

我写了一个c ++程序fllow(3.43.cpp):

#include <iostream>
using std::cout;
using std::endl;

void version_1(int **arr) {
    for (const int (&p)[4] : arr) {
        for (int q : p) {
            cout << q << " ";
        }
        cout << endl;
    }
}

int main() {
    int arr[3][4] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
    version_1(arr);
    return 0;
}

然后我使用:编译它gcc my.cpp -std=c++11,有一个我无法处理的错误.信息:

3.43.cpp:6:30: error: no matching function for call to ‘begin(int**&)’
     for (const int (&p)[4] : arr) { …

这是"C编程语言"一书中的程序.
有一个错误:'strdup'的冲突类型!当遇到函数'strdup'时.但是如果你将'strdup'改为其他名称,例如'strdu',错误就会消失.
我不知道为什么？顺便说一下,我使用code :: blocks作为我的IDE.

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>

#define MAXWORD 100

struct tnode {
    char *word;           
    int count;           
    struct tnode *left;   
    struct tnode *right; 
};

struct tnode *addtree(struct tnode *, char *);
struct tnode *talloc(void);

void treeprint(struct tnode *);
int getword(char *, int);
char *strdup(char *);

/*  word frequency count */
int main()
{
    struct tnode *root;
    char word[MAXWORD];

    root = NULL;
    while (getword(word, MAXWORD) != EOF)
        if (isalpha(word[0]))
            root = addtree(root, word);
    treeprint(root); …

Sales_data.h

#ifndef SALES_DATA_H
#define SALES_DATA_H
#include <string>

class Sales_data {
    friend std::istream &read(std::istream &in, Sales_data &data);
    friend std::ostream &print(std::ostream &out, const Sales_data &data);

public:
    Sales_data() = default;
    //Sales_data(std::string _bookNo="", unsigned _units_sold = 0, double _revenue = 0)
        //:bookNo(_bookNo), units_sold(_units_sold), revenue(_revenue) {}
    std::string isbn() { return bookNo; }
    Sales_data& combine(const Sales_data&);
    double avg_price() const;
private:
    std::string bookNo;
    unsigned units_sold = 0;
    double revenue = 0;
};

Sales_data &Sales_data::combine(const Sales_data& data) {
    units_sold += data.units_sold;
    revenue += data.revenue;
    return *this;
}

std::istream …