利用银行家算法避免死锁c语言

银行家算法是一种操作系统中用于避免死锁的算法。它通过动态地分配资源来避免死锁的发生。在银行家算法中，系统会对每个进程的资源请求进行检查，如果该请求导致系统进入不安全状态，则该请求将被拒绝，否则该请求将被满足。C语言是一种常用的编程语言，可以用来实现银行家算法。

以下是利用C语言实现银行家算法的基本步骤：
1. 定义进程数和资源数，以及每个进程的最大需求量、已分配资源量和需要资源量。
2. 定义可用资源量和安全序列。
3. 实现银行家算法的主要函数，包括安全性检查函数和资源分配函数。
4. 在主函数中调用银行家算法函数，输出安全序列或死锁信息。

以下是一个简单的C语言实现银行家算法的例子：

#include <stdio.h>
#define MAX_PROCESS 10
#define MAX_RESOURCE 10

int available[MAX_RESOURCE];
int max[MAX_PROCESS][MAX_RESOURCE];
int allocation[MAX_PROCESS][MAX_RESOURCE];
int need[MAX_PROCESS][MAX_RESOURCE];
int work[MAX_RESOURCE];
int finish[MAX_PROCESS];

int safety_check(int n, int m) {
    int i, j, k, count = 0;
    for (i = 0; i < m; i++) {
        work[i] = available[i];
    }
    for (i = 0; i < n; i++) {
        finish[i] = 0;
    }
    while (count < n) {
        int found = 0;
        for (i = 0; i < n; i++) {
            if (!finish[i]) {
                int flag = 1;
                for (j = 0; j < m; j++) {
                    if (need[i][j] > work[j]) {
                        flag = 0;
                        break;
                    }
                }
                if (flag) {
                    for (k = 0; k < m; k++) {
                        work[k] += allocation[i][k];
                    }
                    finish[i] = 1;
                    found = 1;
                    count++;
                }
            }
        }
        if (!found) {
            return 0;
        }
    }
    return 1;
}

int resource_request(int pid, int request[], int n, int m) {
    int i, j;
    for (i = 0; i < m; i++) {
        if (request[i] > need[pid][i] || request[i] > available[i]) {
            return 0;
        }
    }
    for (i = 0; i < m; i++) {
        available[i] -= request[i];
        allocation[pid][i] += request[i];
        need[pid][i] -= request[i];
    }
    if (!safety_check(n, m)) {
        for (i = 0; i < m; i++) {
            available[i] += request[i];
            allocation[pid][i] -= request[i];
            need[pid][i] += request[i];
        }
        return 0;
    }
    return 1;
}

int main() {
    int n, m, i, j;
    printf("Enter the number of processes: ");
    scanf("%d", &n);
    printf("Enter the number of resources: ");
    scanf("%d", &m);
    printf("Enter the available resources: ");
    for (i = 0; i < m; i++) {
        scanf("%d", &available[i]);
    }
    printf("Enter the maximum demand of each process: ");
    for (i = 0; i < n; i++) {
        for (j = 0; j < m; j++) {
            scanf("%d", &max[i][j]);
        }
    }
    printf("Enter the allocated resources of each process: ");
    for (i = 0; i < n; i++) {
        for (j = 0; j < m; j++) {
            scanf("%d", &allocation[i][j]);
            need[i][j] = max[i][j] - allocation[i][j];
        }
    }
    if (safety_check(n, m)) {
        printf("The system is in safe state.\n");
    } else {
        printf("The system is in unsafe state.\n");
    }
    int pid;
    int request[MAX_RESOURCE];
    printf("Enter the process id and resource request: ");
    scanf("%d", &pid);
    for (i = 0; i < m; i++) {
        scanf("%d", &request[i]);
    }
    if (resource_request(pid, request, n, m)) {
        printf("The request is granted.\n");
    } else {
        printf("The request is denied.\n");
    }
    return 0;
}