银行家算法（安全性检测及资源申请分配）c语言

下面是一个简单的银行家算法的C语言实现，仅供参考：

#include <stdio.h>
#include <stdbool.h>

// 定义进程数和资源数的最大值
#define MAX_PROCESS 100
#define MAX_RESOURCES 100

// 进程结构体，用于存储每个进程的信息
typedef struct {
    int id; // 进程ID
    int max[MAX_RESOURCES]; // 最大资源需求量
    int allocated[MAX_RESOURCES]; // 已分配的资源量
    int need[MAX_RESOURCES]; // 资源需求量
    bool finished; // 进程是否完成
} Process;

// 全局变量，存储系统中的进程和资源
Process processes[MAX_PROCESS];
int available[MAX_RESOURCES];
int n_processes, n_resources;

// 比较两个资源向量是否相等
bool is_equal(int a[], int b[]) {
    for (int i = 0; i < n_resources; i++) {
        if (a[i] != b[i]) {
            return false;
        }
    }
    return true;
}

// 比较资源向量a是否小于等于资源向量b
bool is_less_than_or_equal(int a[], int b[]) {
    for (int i = 0; i < n_resources; i++) {
        if (a[i] > b[i]) {
            return false;
        }
    }
    return true;
}

// 处理资源请求
bool request_resources(int pid, int request[]) {
    // 检查请求是否合法
    if (!is_less_than_or_equal(request, processes[pid].need)) {
        return false;
    }
    if (!is_less_than_or_equal(request, available)) {
        return false;
    }

    // 假设分配资源后不会出现死锁
    for (int i = 0; i < n_resources; i++) {
        available[i] -= request[i];
        processes[pid].allocated[i] += request[i];
        processes[pid].need[i] -= request[i];
    }

    // 检查是否出现死锁
    bool is_safe = false;
    int work[n_resources];
    bool finish[n_processes];
    for (int i = 0; i < n_processes; i++) {
        finish[i] = processes[i].finished;
    }
    while (!is_safe) {
        // 搜索未完成的进程
        int i;
        for (i = 0; i < n_processes; i++) {
            if (!finish[i] && is_less_than_or_equal(processes[i].need, available)) {
                break;
            }
        }
        if (i == n_processes) {
            break;
        }

        // 分配资源
        for (int j = 0; j < n_resources; j++) {
            work[j] = available[j];
        }
        for (int j = 0; j < n_resources; j++) {
            available[j] += processes[i].allocated[j];
            processes[i].allocated[j] = 0;
            processes[i].need[j] = 0;
            processes[i].finished = true;
        }

        // 检查是否出现死锁
        bool is_finish = true;
        for (int j = 0; j < n_processes; j++) {
            if (!finish[j] && is_less_than_or_equal(processes[j].need, available)) {
                is_finish = false;
                break;
            }
        }
        if (is_finish) {
            is_safe = true;
        }
        else {
            for (int j = 0; j < n_resources; j++) {
                available[j] = work[j];
            }
            for (int j = 0; j < n_resources; j++) {
                processes[i].allocated[j] += request[j];
                processes[i].need[j] -= request[j];
            }
            processes[i].finished = false;
        }
    }

    // 如果出现死锁，撤销资源分配
    if (!is_safe) {
        for (int i = 0; i < n_resources; i++) {
            available[i] += request[i];
            processes[pid].allocated[i] -= request[i];
            processes[pid].need[i] += request[i];
        }
        return false;
    }

    return true;
}

int main() {
    // 输入进程数和资源数
    printf("Enter number of processes: ");
    scanf("%d", &n_processes);
    printf("Enter number of resources: ");
    scanf("%d", &n_resources);

    // 输入每个进程的最大资源需求量和已分配的资源量
    for (int i = 0; i < n_processes; i++) {
        printf("Enter max resource needs for process %d: ", i);
        for (int j = 0; j < n_resources; j++) {
            scanf("%d", &processes[i].max[j]);
            processes[i].need[j] = processes[i].max[j];
        }
        printf("Enter allocated resources for process %d: ", i);
        for (int j = 0; j < n_resources; j++) {
            scanf("%d", &processes[i].allocated[j]);
            processes[i].need[j] -= processes[i].allocated[j];
        }
        processes[i].id = i;
        processes[i].finished = false;
    }

    // 输入系统中每种资源的总量
    printf("Enter available resources: ");
    for (int i = 0; i < n_resources; i++) {
        scanf("%d", &available[i]);
    }

    // 处理资源请求
    int pid, request[MAX_RESOURCES];
    printf("Enter process ID and resource request (e.g. 1 2 3): ");
    scanf("%d", &pid);
    for (int i = 0; i < n_resources; i++) {
        scanf("%d", &request[i]);
    }
    if (request_resources(pid, request)) {
        printf("Request granted.\n");
    }
    else {
        printf("Request denied.\n");
    }

    return 0;
}