c语言中改变了这个#include<iostream>，怎么改变这个#include<malloc.h>

在 C 语言中，可以使用 `#include<stdlib.h>` 来代替 `#include<malloc.h>`，因为 `malloc` 函数和其他动态内存分配函数都在 `stdlib.h` 头文件中声明。因此，只需要将包含 `malloc.h` 的代码行改为 `#include<stdlib.h>` 即可。例如：

#include <stdlib.h>

int main() {
    int *ptr = (int*) malloc(sizeof(int));
    *ptr = 42;
    free(ptr);
    return 0;
}

上面的代码使用了 `malloc` 函数，但是使用的是 `stdlib.h` 头文件。

相关问题

#include <iostream> #include <vector> using namespace std; int main() { int n; while (cin >> n) { vector<int> nums(n); for (int i = 0; i < n; i++) { cin >> nums[i]; } int count = 0; for (int i = 1; i < n - 1; i++) { int left = 0, right = n - 1; while (left < i && right > i) { int sum = nums[left] + nums[right]; if (sum == nums[i] * 2) { count++; break; } else if (sum < nums[i] * 2) { left++; } else { right--; } } } cout << count << endl; } return 0; }将这个代码转化为c语言代码

以下是将该代码转化为 C 语言代码的过程：

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

int main() {
    int n;
    while (scanf("%d", &n) != EOF) {
        int* nums = (int*) malloc(n * sizeof(int));
        for (int i = 0; i < n; i++) {
            scanf("%d", &nums[i]);
        }
        int count = 0;
        for (int i = 1; i < n - 1; i++) {
            int left = 0, right = n - 1;
            while (left < i && right > i) {
                int sum = nums[left] + nums[right];
                if (sum == nums[i] * 2) {
                    count++;
                    break;
                } else if (sum < nums[i] * 2) {
                    left++;
                } else {
                    right--;
                }
            }
        }
        printf("%d\n", count);
        free(nums);
    }
    return 0;
}

主要的修改如下：

- `#include <iostream>` 改为 `#include <stdio.h>`。
- `using namespace std;` 去掉。
- `cin` 改为 `scanf`。
- `vector<int> nums(n);` 改为 `int* nums = (int*) malloc(n * sizeof(int));`，使用 `malloc` 分配动态数组。
- `cout` 改为 `printf`。
- 添加了 `free(nums)` 释放动态数组内存。

用C语言改一下#include<iostream> #include<cstring> #include<iomanip> using namespace std; struct student{ char name[20]; int num; //学号 int number; //票数 int Class; char major[30]; char grade[10]; char achievement[200]; }; class votesystem{ private: studentst; int count; //当前元素个数 int size; //哈希表长 public: void InitHashTable(int n); //初始化哈希表 int Hash(charname); //计算哈希地址 void collision(int &s); //冲突，计算下一个地址 int search(char name,int &s); //查找 void insert(charname); //插入 int vote(char*name); //投票 void display(); //显示哈希表 void showvote(int k); //按哈希表下标显示票数 void showrank(); //显示排行榜 };

使用C语言改写该代码如下：

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

#define MAX_NAME_LEN 20
#define MAX_MAJOR_LEN 30
#define MAX_GRADE_LEN 10
#define MAX_ACHIEVEMENT_LEN 200
#define HASH_TABLE_SIZE 100

typedef struct student {
    char name[MAX_NAME_LEN];
    int num; //学号
    int number; //票数
    int Class;
    char major[MAX_MAJOR_LEN];
    char grade[MAX_GRADE_LEN];
    char achievement[MAX_ACHIEVEMENT_LEN];
} student;

typedef struct HashNode {
    student st;
    int flag; //标记该位置是否被占用
} HashNode;

typedef struct votesystem {
    HashNode table[HASH_TABLE_SIZE];
    int count; //当前元素个数
} votesystem;

void InitHashTable(votesystem *vs) {
    vs->count = 0;
    for (int i = 0; i < HASH_TABLE_SIZE; i++) {
        vs->table[i].flag = 0;
    }
}

int Hash(char *name) {
    int hash_val = 0;
    for (int i = 0; name[i] != '\0'; i++) {
        hash_val = (hash_val * 31 + name[i]) % HASH_TABLE_SIZE;
    }
    return hash_val;
}

void collision(int *s) {
    (*s)++;
    if (*s == HASH_TABLE_SIZE) {
        *s = 0;
    }
}

int search(votesystem *vs, char *name, int *s) {
    int hash_val = Hash(name);
    while (vs->table[hash_val].flag != 0 && strcmp(vs->table[hash_val].st.name, name) != 0) {
        collision(s);
        hash_val = Hash(name) + *s;
    }
    if (vs->table[hash_val].flag == 0) {
        return -1; //未找到该元素
    } else {
        return hash_val;
    }
}

void insert(votesystem *vs, student st) {
    if (vs->count == HASH_TABLE_SIZE) {
        printf("Hash table is full!\n");
    } else {
        int s = 0;
        int hash_val = Hash(st.name);
        while (vs->table[hash_val].flag == 1) {
            collision(&s);
            hash_val = Hash(st.name) + s;
        }
        vs->table[hash_val].st = st;
        vs->table[hash_val].flag = 1;
        vs->count++;
    }
}

int vote(votesystem *vs, char *name) {
    int s = 0;
    int hash_val = search(vs, name, &s);
    if (hash_val == -1) {
        printf("Student %s not found!\n", name);
        return -1;
    } else {
        vs->table[hash_val].st.number++;
        return vs->table[hash_val].st.number;
    }
}

void display(votesystem *vs) {
    for (int i = 0; i < HASH_TABLE_SIZE; i++) {
        if (vs->table[i].flag == 1) {
            printf("name: %s, num: %d, number: %d, Class: %d, major: %s, grade: %s, achievement: %s\n",
                   vs->table[i].st.name, vs->table[i].st.num, vs->table[i].st.number,
                   vs->table[i].st.Class, vs->table[i].st.major, vs->table[i].st.grade,
                   vs->table[i].st.achievement);
        }
    }
}

void showvote(votesystem *vs, int k) {
    if (k >= 0 && k < HASH_TABLE_SIZE && vs->table[k].flag == 1) {
        printf("name: %s, number: %d\n", vs->table[k].st.name, vs->table[k].st.number);
    } else {
        printf("Invalid index!\n");
    }
}

void showrank(votesystem *vs) {
    student *tmp_st = (student *) malloc(sizeof(student) * vs->count);
    int tmp_count = 0;
    for (int i = 0; i < HASH_TABLE_SIZE; i++) {
        if (vs->table[i].flag == 1) {
            tmp_st[tmp_count++] = vs->table[i].st;
        }
    }
    for (int i = 0; i < tmp_count - 1; i++) {
        for (int j = i + 1; j < tmp_count; j++) {
            if (tmp_st[i].number < tmp_st[j].number) {
                student tmp = tmp_st[i];
                tmp_st[i] = tmp_st[j];
                tmp_st[j] = tmp;
            }
        }
    }
    for (int i = 0; i < tmp_count; i++) {
        printf("%d. name: %s, number: %d\n", i + 1, tmp_st[i].name, tmp_st[i].number);
    }
    free(tmp_st);
}

int main() {
    votesystem vs;
    InitHashTable(&vs);
    student st1 = {"Tom", 1001, 0, 1, "Computer Science", "Grade 1", "Excellent"};
    student st2 = {"Jerry", 1002, 0, 1, "Computer Science", "Grade 1", "Good"};
    student st3 = {"Bob", 1003, 0, 1, "Computer Science", "Grade 1", "Average"};
    insert(&vs, st1);
    insert(&vs, st2);
    insert(&vs, st3);
    vote(&vs, "Tom");
    vote(&vs, "Jerry");
    vote(&vs, "Tom");
    vote(&vs, "Tom");
    display(&vs);
    showvote(&vs, Hash("Tom"));
    showrank(&vs);
    return 0;
}