【发布时间】：2020-05-01 03:45:58
【问题描述】：
如何解决此错误？这是由于将我的数组 pgAccess、pgArray 和 pgRequest 初始化为可变大小，这些都是整个程序中使用的全局变量。我知道某些方法中可能存在一些未声明的变量，但我想关注这些数组的问题。我在这里使用虚拟内存算法。
int flag = 0, var, currFrame = 0, numFault, currRequest, request;
int numPages, numFrames, numRequest, fc =0, go =0, c =0;
int pgAccess[numRequest], pgArray[numPages], pgRequest[numRequest];
void runningMessage(int, int, int);
void fifo();
void lru();
void opt();
void runningMessage(int pg, int frame, int msg){
if(msg == 1)
{
printf("Page %d already in Frame %d\n",pg, frame);
}
if(msg == 2)
{
printf("Page %d loaded into Frame %d\n",pg, frame);
}
if(msg == 3)
{
printf("Page %d unloaded from Fram %d\n",pg, frame);
}
}
int main(int argc, char *argv[])
{
FILE *fp;
fp = fopen(argv[1], "r");
int x =0;
fscanf(fp, "%d %d %d", &numPages, &numFrames, &numRequest);
while(!feof(fp))
{
fscanf(fp, "%d", &pgAccess[x]);
x++;
}
fclose(fp);
printf("Algorithm: %s\n\n", argv[2]);
if(argv[2] == "FIFO")
{
fifo();
}
if(argv[2] == "LRU")
{
lru();
}
if(argv[3] == "OPT")
{
opt();
}
}
void fifo(){
int i, x;
for(i = 0; i < numFrames; i++)
{
pgArray[i] = -1;
}
while(x < numRequest)
{
flag =0;
var = pgAccess[x];
for(i = 0; i < numFrames; i++)
{
if(var == pgArray[i])
{
flag = 1;
x++;
runningMessage(pgArray[i], i, 1);
break;
}
}
if(flag == 0)
{
if(currFrame < numFrames)
{
pgArray[currFrame] = pgAccess[x];
runningMessage(pgAccess[x], currFrame, 2);
currFrame++;
x++;
numFault++;
}
else if( y < numFrames)
{
runningMessage(pgArray[y], y, 3);
pgArray[y] = pgAccess[x];
runningMessage(pgAccess[x], y, 2);
x++;
y++;
numFault++;
else
{
y =0;
}
}
}
}
printf(" %d Page Faults\n\n", numFault);
}
void lru(){
int i, x, y, a, b, j;
y = numFrames;
for(i = 0; i < y; i++)
{
pgRequest[i] = 0;
pgArray[i] = -1;
}
for(i = 0; i < numRequest; i++)
{
flag = 0;
a = pgAccess[i];
for(j = 0; j < y; j++)
{
if(a == pgArray[j])
{
flag = 1;
pgRequest[j] = i;
runningMessage(pgArray[j], j, 1);
break;
}
}
if((flag == 0) && (b < y))
{
fc++;
pgArray[b] = a;
pgRequest[b] = i;
runningMessage(pgArray[b], b, 2);
b++;
}
else if((flag == 0) && (b == y))
{
fc++;
minRequest = pgRequest[0];
for(currRequest = 0; currRequest < y; currRequest++)
{
if(pgRequest[currRequest] < minRequest)
{
minRequest = pgRequest[currRequest];
request = currRequest;
}
}
pgArray[request] = a;
pgRequest[request] = i;
runningMessage(pgAccess[request], request, 3);
runningMessage(pgArray[request], request, 2);
request =0;
}
}
printf(" %d Page Faults\n\n", fc);
}
void opt(){
int i, x, y, a;
for(i = 0; i < numFrames; i++)
{
pgRequest[i] = 0;
pgArray[i] = -1;
}
for(i = 0; i < numRequest; i++)
{
flag = 0;
a = pgAccess[i];
for(y = 0; y < numFrames, y++)
{
if(a == pgArray[y])
{
flag = 1;
runningMessage(pgArray[y], y, 1);
break;
}
}
if((flag == 0) && (x < numFrames))
{
fc++;
pgArray[x] = a;
runningMessage(pgArray[x], x, 2);
x++;
}
else if((flag == 0) && (x == numFrames))
{
fc++;
for(go = 0; go < numFrames; go++)
{
pgRequest[go] = 0;
}
for(currRequest = 0; currRequest < numFrames; currRequest++)
{
c = 0;
for(currFrame = i + 1; currFrame < numRequest; currFrame++);
{
if(pgArray[currRequest] == pgAccess[currFrame])
{
if(pgRequest[currRequest] == 0)
{
pgRequest[currRequest] = currFrame;
c = 1;
}
}
}
if(c != 1)
{
pgRequest[currRequest] = numRequest + 1;
}
}
request = 0;
maxRequest = pgRequest[0];
for(go = 0; go < numFrames; go++)
{
if(pgRequest[go] > maxRequest)
{
maxRequest = pgRequest[go];
runningMessage(pgArray[go], go, 3);
request = go;
}
}
pgArray[request] = a;
runningMessage(pgArray[request], request, 2);
}
}
printf(" %d Page Faults\n\n", fc);
}
【问题讨论】：
-
首先，你必须使用 strcmp 而不是 if(argv[2] == "FIFO")
-
你说得对，我会改的
-
How can I fix this error?什么错误？请参阅How to create a Minimal, Reproducible Example。 -
pgAcces[numRequests]变量numRequests在这里未定义。使用malloc。 -
很难回答你的问题，因为代码太多了。如果您可以删除与您的问题不直接相关的任何内容并创建minimal reproducible example，这将真正帮助我们。如果精简后的程序不是特别有用，那很好，只要它仍然能证明问题。例如，您可以硬编码用户输入，或用预设结果替换函数调用。这不仅仅是为了我们的利益；在创建 MRE 时，您可能会自己找出答案！