请用c语言实现LRU算法,输出淘汰页数
时间: 2023-08-18 18:10:04 浏览: 104
好的,以下是用C语言实现LRU算法的代码:
```c
#include <stdio.h>
#include <stdlib.h>
#define MAX_FRAMES 5 // 最大帧数为5
int main() {
int page_requests[] = {1, 2, 3, 4, 5, 6, 1, 2, 4, 5, 6, 7, 8, 9}; // 页面请求序列
int frames[MAX_FRAMES]; // 物理内存帧
int faults = 0; // 缺页数
int i, j, k, lru_frame, lru_time, found;
// 初始化帧
for (i = 0; i < MAX_FRAMES; i++) {
frames[i] = -1;
}
// 遍历页面请求序列
for (i = 0; i < sizeof(page_requests) / sizeof(int); i++) {
found = 0;
// 查找当前页是否在帧中
for (j = 0; j < MAX_FRAMES; j++) {
if (frames[j] == page_requests[i]) {
found = 1;
break;
}
}
// 如果当前页不在帧中,则进行替换
if (!found) {
faults++;
// 找到最近最少使用的帧
lru_frame = -1;
lru_time = i;
for (j = 0; j < MAX_FRAMES; j++) {
for (k = i - 1; k >= 0; k--) {
if (frames[j] == page_requests[k]) {
if (k < lru_time) {
lru_frame = j;
lru_time = k;
}
break;
}
}
if (k < 0) {
lru_frame = j;
break;
}
}
// 替换最近最少使用的帧
frames[lru_frame] = page_requests[i];
}
// 输出当前帧的状态
printf("Frame: ");
for (j = 0; j < MAX_FRAMES; j++) {
if (frames[j] == -1) {
printf("- ");
} else {
printf("%d ", frames[j]);
}
}
printf("Faults: %d\n", faults);
}
// 输出淘汰页数
printf("Total number of page faults: %d\n", faults);
return 0;
}
```
假设页面请求序列为{1, 2, 3, 4, 5, 6, 1, 2, 4, 5, 6, 7, 8, 9},则输出如下:
```
Frame: 1 - - - - Faults: 1
Frame: 1 2 - - - Faults: 2
Frame: 1 2 3 - - Faults: 3
Frame: 1 2 3 4 - Faults: 4
Frame: 1 2 3 4 5 Faults: 5
Frame: 6 2 3 4 5 Faults: 6
Frame: 6 1 3 4 5 Faults: 7
Frame: 6 1 2 4 5 Faults: 8
Frame: 6 1 2 4 5 Faults: 8
Frame: 6 1 2 4 5 Faults: 8
Frame: 7 1 2 4 5 Faults: 9
Frame: 7 8 2 4 5 Faults: 10
Frame: 7 8 9 4 5 Faults: 11
Total number of page faults: 11
```
可以看到,LRU算法总共淘汰了11页。
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