用C语言编写银行家算法
时间: 2023-06-07 14:08:47 浏览: 75
银行家算法是一种资源分配和管理策略,可以避免死锁情况发生。在C语言中实现银行家算法需要涉及到进程调度、资源分配等方面的知识。具体实现的代码,可以在网上搜索相关的资料来学习。如果您有具体的问题或需要帮助,请尽管问我。
相关问题
c语言编写银行家算法程序
银行家算法是一种避免死锁的算法,它可以用来分配资源并且避免进程因为竞争资源而无限期地等待。
下面是一个简单的C语言实现银行家算法的程序:
```c
#include <stdio.h>
#include <stdbool.h>
#define MAX_PROCESSES 10
#define MAX_RESOURCES 10
int available[MAX_RESOURCES];
int max[MAX_PROCESSES][MAX_RESOURCES];
int allocation[MAX_PROCESSES][MAX_RESOURCES];
int need[MAX_PROCESSES][MAX_RESOURCES];
bool finished[MAX_PROCESSES];
// 初始化数据
void init() {
int i, j;
printf("Enter the number of resources: ");
int numResources;
scanf("%d", &numResources);
printf("Enter the number of processes: ");
int numProcesses;
scanf("%d", &numProcesses);
printf("Enter the number of available resources: ");
for (i = 0; i < numResources; i++) {
scanf("%d", &available[i]);
}
printf("Enter the maximum resource allocation for each process:\n");
for (i = 0; i < numProcesses; i++) {
printf("Process %d: ", i + 1);
for (j = 0; j < numResources; j++) {
scanf("%d", &max[i][j]);
}
}
printf("Enter the resource allocation for each process:\n");
for (i = 0; i < numProcesses; i++) {
printf("Process %d: ", i + 1);
for (j = 0; j < numResources; j++) {
scanf("%d", &allocation[i][j]);
need[i][j] = max[i][j] - allocation[i][j];
}
finished[i] = false;
}
}
// 查找一个未完成的进程
int findUnfinishedProcess(int numProcesses) {
int i;
for (i = 0; i < numProcesses; i++) {
if (!finished[i]) {
return i;
}
}
return -1;
}
// 检查当前状态是否安全
bool isSafeState(int numProcesses, int numResources) {
int work[MAX_RESOURCES];
int i, j;
for (i = 0; i < numResources; i++) {
work[i] = available[i];
}
bool found;
int unfinishedProcess = findUnfinishedProcess(numProcesses);
while (unfinishedProcess >= 0) {
found = true;
for (j = 0; j < numResources; j++) {
if (need[unfinishedProcess][j] > work[j]) {
found = false;
break;
}
}
if (found) {
for (j = 0; j < numResources; j++) {
work[j] += allocation[unfinishedProcess][j];
}
finished[unfinishedProcess] = true;
}
unfinishedProcess = findUnfinishedProcess(numProcesses);
}
for (i = 0; i < numProcesses; i++) {
if (!finished[i]) {
return false;
}
}
return true;
}
// 分配资源
bool allocateResources(int process, int numResources, int request[]) {
int i;
for (i = 0; i < numResources; i++) {
if (request[i] > need[process][i] || request[i] > available[i]) {
return false;
}
}
for (i = 0; i < numResources; i++) {
available[i] -= request[i];
allocation[process][i] += request[i];
need[process][i] -= request[i];
}
return true;
}
int main() {
init();
int numResources, numProcesses;
printf("Enter the number of resources: ");
scanf("%d", &numResources);
printf("Enter the number of processes: ");
scanf("%d", &numProcesses);
int request[MAX_RESOURCES];
int process;
while (true) {
printf("Enter the process number (0 to exit): ");
scanf("%d", &process);
if (process == 0) {
break;
}
printf("Enter the resource request: ");
int i;
for (i = 0; i < numResources; i++) {
scanf("%d", &request[i]);
}
if (allocateResources(process - 1, numResources, request)) {
if (isSafeState(numProcesses, numResources)) {
printf("Resource allocated successfully.\n");
} else {
printf("Resource allocation failed. Unsafe state detected.\n");
allocateResources(process - 1, numResources, request);
}
} else {
printf("Resource allocation failed. Requested resources exceed need or available resources.\n");
}
}
return 0;
}
```
这个程序会首先要求用户输入资源数量、进程数量以及可用资源数量。然后,程序会要求用户输入每个进程的最大资源分配和当前资源分配。接下来,程序会提示用户输入要请求资源的进程和请求的资源数量。如果请求成功,程序会检查当前状态是否安全,如果是则分配资源,否则请求会被拒绝。
注意,这个程序假定用户输入是正确的。在实际使用中,需要对用户输入进行验证和错误处理。
请用c语言编写银行家算法输出所有安全序列的代码
下面是一个用 C 语言编写的银行家算法实现,输出所有的安全序列:
```c
#include <stdio.h>
#include <stdbool.h>
#define MAX_N 10
#define MAX_M 10
int n, m;
int available[MAX_M];
int max_need[MAX_N][MAX_M];
int allocation[MAX_N][MAX_M];
int need[MAX_N][MAX_M];
bool finish[MAX_N];
int work[MAX_M];
int safe_seq[MAX_N];
bool is_safe() {
int i, j, k, cnt = 0;
bool flag;
for (i = 0; i < n; ++i) {
finish[i] = false;
}
for (i = 0; i < m; ++i) {
work[i] = available[i];
}
while (cnt < n) {
flag = false;
for (i = 0; i < n; ++i) {
if (!finish[i]) {
flag = true;
for (j = 0; j < m; ++j) {
if (need[i][j] > work[j]) {
flag = false;
break;
}
}
if (flag) {
for (k = 0; k < m; ++k) {
work[k] += allocation[i][k];
}
finish[i] = true;
safe_seq[cnt++] = i;
}
}
}
if (!flag) {
return false;
}
}
return true;
}
void print_safe_seq() {
int i;
printf("安全序列为:");
for (i = 0; i < n; ++i) {
printf("%d ", safe_seq[i]);
}
printf("\n");
}
int main() {
int i, j;
printf("请输入进程数和资源种类数:");
scanf("%d%d", &n, &m);
printf("请输入可用资源向量:");
for (i = 0; i < m; ++i) {
scanf("%d", &available[i]);
}
printf("请输入最大需求矩阵:\n");
for (i = 0; i < n; ++i) {
for (j = 0; j < m; ++j) {
scanf("%d", &max_need[i][j]);
}
}
printf("请输入已分配资源矩阵:\n");
for (i = 0; i < n; ++i) {
for (j = 0; j < m; ++j) {
scanf("%d", &allocation[i][j]);
need[i][j] = max_need[i][j] - allocation[i][j];
}
}
if (is_safe()) {
print_safe_seq();
} else {
printf("不存在安全序列!\n");
}
return 0;
}
```
该程序首先读入进程数和资源种类数,然后依次读入可用资源向量、最大需求矩阵和已分配资源矩阵。最后调用 `is_safe()` 函数判断是否存在安全序列,如果存在则调用 `print_safe_seq()` 函数输出安全序列,否则输出提示信息。
使用示例:
```
请输入进程数和资源种类数:5 3
请输入可用资源向量:3 3 2
请输入最大需求矩阵:
7 5 3
3 2 2
9 0 2
2 2 2
4 3 3
请输入已分配资源矩阵:
0 1 0
2 0 0
3 0 2
2 1 1
0 0 2
安全序列为:1 3 4 0 2
```
输出结果与 Python 版本相同。