使用 sscanf 进行解析不会保留数组以供后续使用

Question

我正在从事一个模拟 n 路关联缓存映射的项目。但是，当尝试在后续等式中使用 address[i] 数组时，问题就出现了。我想我不明白为什么数组没有被保留。任何帮助将不胜感激。我不是最擅长 C 编码的人。现在的问题是从文件中读取并将这些值扫描到数组中。我相信我能弄清楚的其他一切。

代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>


/*global variables */
int mainSize, cacheSize, blockSize, cmSet, cnumBlocks, mnumBlocks,address[50],mmBlkNum[50], mappedCMset[50],hit_miss[50],address[50];
char mode[50];
int totMemRefs=0;


int main(void)
{
    /*Variables */

    int i;
    char replacePolicy;
    char filename[50];
    char *result = NULL;
    char line[50];
    FILE *fp;
    fp = fopen(filename, "r");


    /*Gathers input from user */
    printf("Enter the main memory size between between 4 and 32K bytes: ");
    scanf("%d",&mainSize);
    if (mainSize < 4 || mainSize > 32768)
    {
        printf("Invalid main memory size.");
        //errorCheck()
    }

    printf("Enter the size of the cache between 2 and 32K bytes: ");
    scanf("%d", &cacheSize);
    if (cacheSize < 2 || cacheSize > 32768)
    {
        printf("Invalid cache memory size.");
        //errorCheck()
    } 


    printf("Enter the size of the block/line between 2 and 32K bytes: ");
    scanf("%d",&blockSize);
    if (blockSize < 2 || blockSize > 32768)
    {
        printf("Invalid block/line size.");
        //errorCheck
    }

    printf("Enter the degree of set-associativity: ");
    scanf("%d", &cmSet);


    cnumBlocks = cacheSize/blockSize;
    printf("Number of blocks in cache = %d\n", cnumBlocks);

    mnumBlocks = mainSize/blockSize;
    printf("Number of blocks in main memory = %d\n", mnumBlocks);

    printf("Enter replacement policy (L = LRU, F = FIFO): ");
    scanf("%s", &replacePolicy);




    printf("Enter the name of the file containing the list of memory    referenced: ");
    scanf("%s", filename);


    /* checks if filename is valid/exits */
    if ((fp = fopen(filename, "r")) == NULL)
    {
        printf("Invalid input.");
        //errorCheck();
    }

    /* gets total number of mem references from first line of file and stores in variable totMemRefs*/
    fgets(line,sizeof(line),fp);
    result = strtok(line,"\n");
    totMemRefs = atoi(result);
    printf("Total Mem Refs = %d\n", totMemRefs);


    /*skips second line of white space */
    fgets(line, sizeof(line),fp);

    i=0;
    //reads each line of file and tokenizes into mode and address
    while (fgets(line, sizeof(line), fp)!=NULL)
    {

        if (sscanf(line,"%s %d",&mode[i],&address[i]) == 2)
        {
            printf("Mode: %c  Address: %d\n",mode[i],address[i]);
            i++;
        }


    }//end of parsing while loop

    fclose(fp); //close file after reading


    for (i=0; i<totMemRefs; i++)
    {
        /* calculates the corresponding block number of the address */
        mmBlkNum[i]=address[i]/blockSize;

        /* calculates the corresponding cache mem set that mm block is in */
        mappedCMset[i]=mmBlkNum[i]%cnumBlocks;
        printf("Mode = %c  Address = %d  MM Block Num = %d  Cm Set = %d\n",    mode[i],address[i],mmBlkNum[i],mappedCMset[i]);

    }

}//end of main

这是example_test_data.txt的内容：

6

R 0
R 1
R 4
R 36
R 0
R 4

这些是主内存和高速缓存的特点：

main mem size = 128 bytes
cache mem size = 32 bytes
block size = 4 bytes
set associativity = 2
filename = example_test_data.txt

这是 while 循环中数组的输出：

    Mode: R  Address: 0
    Mode: R  Address: 1
    Mode: R  Address: 4
    Mode: R  Address: 36
    Mode: R  Address: 0
    Mode: R  Address: 4

这是解析后数组的输出 -- 在以下 for 循环中：

    Mode = R  Address = 4  MM Block Num = 1  Cm Set = 1
    Mode =    Address = 0  MM Block Num = 0  Cm Set = 0
    Mode =    Address = 0  MM Block Num = 0  Cm Set = 0
    Mode =    Address = 0  MM Block Num = 0  Cm Set = 0
    Mode =    Address = 0  MM Block Num = 0  Cm Set = 0
    Mode =    Address = 0  MM Block Num = 0  Cm Set = 0

如您所见，模式和地址数组的第二次迭代与文件 while 循环中的不同。我对为什么会这样感到困惑。我试图尽可能地描述。我也不知道为什么格式没有出现。对不起，如果这使它更难阅读。同样，我们将不胜感激任何朝着正确方向提供的帮助或推动！

编辑：输出应该是：

    Mode = R   Address = 0   MM Blk Num = 0   CM Set = 0
    Mode = R   Address = 1   MM Blk Num = 0   CM Set = 0
    Mode = R   Address = 4   MM Blk Num = 1   CM Set = 1
    Mode = R   Address = 36  MM Blk Num = 9   CM Set = 1
    Mode = R   Address = 0   MM Blk Num = 0   CM Set = 0
    Mode = R   Address = 4   MM Blk Num = 1   CM Set = 1

我知道获得正确值所需的方程式。我知道如何手工处理这些没问题。所以知道结果应该是什么不是问题。以前，我使用过 fscanf 和 strtok，但都没有产生预期的结果。基本上，当我在扫描时在 while 循环中打印它时，它会起作用，但是一旦我尝试计算 mmBlkNum 和 mappedCMset，数组中的值就不一样了。

代码已更新！！

Answer 1

我看到的第一个错误：

scanf("%s", &filename);

替换为正确的参数：

scanf("%s", filename);

请使用 -Wall 进行编译，这样编译器就会说出这些内容。结合 -Werror。 -Wextra也推荐。

我的编译器输出你的程序：

Whosebug.c: In function 'main':
Whosebug.c:246:11: error: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[50]' [-Werror=format=]
     scanf("%s", &filename);
           ^
cc1.exe: all warnings being treated as errors

我看到的第二个错误：您将阅读的所有内容放在 i = 0 循环中的同一索引处。使用 for 或正确使用 while：

    i = 0;
    while (fgets(line, sizeof(line), fp)!=NULL && i < totMemRefs)
    {
        if (sscanf(line,"%s %d",&mode[i],&address[i]) == 2)
        {
            printf("Mode: %c  Address: %d\n",mode[i],address[i]);
            i++;
        }


    }//end of parsing while loop

    if (i < totMemRefs)
    {
        fprintf(stderr, "Missing inputs.\n");
        return 1;
    }

我还添加了验证输入不超过用户说他将提供的输入数量，验证用户提供所有行。考虑在程序开头添加类似的内容：

#define MAX_INPUT_LINES 50

并使用 MAX_INPUT_LINES 而不是 50。

使用 sscanf 进行解析不会保留数组以供后续使用

Parsing using sscanf doesn't preserve arrays for subsequent use

c

arrays

parsing

scanf

fgets