c - 通过函数 : FILE* or FILE**? 的 FILE* 数组

Question

我正在尝试制作一个可以同时处理多个不同文件的程序。我的想法是制作一个包含 20 个 FILE* 的数组，以便在我达到此限制时能够关闭其中一个并打开请求的新文件。 为此，我想到了一个函数，它选择一个选项并调用另一个函数来完成保存(写入)、关闭和打开的工作。 在网上搜索半周并进行一些证明后，我制作了两个似乎有效的版本:一个带有 FILE*，另一个带有 FILE**。

我的问题是:如果其中一些有我无法检测到的错误，或者在传递这两个函数时指针使用不当。

(我展示的代码先后有两个函数的两个版本。)

MyProgram() {

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

/* The contents of myFile1a.dat, myFile2b.dat,... are just 5 ints. */


/* Version without pointer to pointer. */
void fReadFile(FILE* pfFile[]) {
    int i = 0, j = 0;
    int iNums[15] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    int iNums2[15] = {5001, 5002, 5003, 5004, 5005, 2033, 2066, 2099, 2133, 2166, 3001, 3002, 3003, 3004, 3005};
    char cNameFile4d[32] = "myFile4d.dat", cNameFile5e[32] = "myFile5e.dat";   
    char cNameFile6f[32] = "myFile6f.dat";
    char cNameFile[32] = {" "};
    int iResultFclose = 0;

    for(i=0; i<5; i++) {
        fread(&iNums[i], 4, 1, pfFile[0]);
        printf("\n%d",iNums[i]);
    }
    for(i=5; i<10; i++) {
        fread(&iNums[i], 4, 1, pfFile[1]);
        printf("\n%d",iNums[i]);
    }
    for(i=10; i<15; i++) {
        fread(&iNums[i], 4, 1, pfFile[2]);
        printf("\n%d", iNums[i]);
    }

    iResultFclose = fclose(pfFile[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose(pfFile[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 1.");
    iResultFclose = fclose(pfFile[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 2.");

    strcpy(cNameFile, cNameFile4d);
    pfFile[0] = fopen(cNameFile, "wb");
    for(i=0; i<5; i++)
        fwrite(&iNums2[i], 4, 1, pfFile[0]);
    strcpy(cNameFile, cNameFile5e);
    pfFile[1] = fopen(cNameFile, "wb");
    for(i=5; i<10; i++)
        fwrite(&iNums2[i], 4, 1, pfFile[1]);
    strcpy(cNameFile, cNameFile6f);
    pfFile[2] = fopen(cNameFile, "wb");
    for(i=10; i<15; i++)
        fwrite(&iNums2[i], 4, 1, pfFile[2]);

    iResultFclose = fclose(pfFile[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose(pfFile[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 1.");
    iResultFclose = fclose(pfFile[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 2.");

    strcpy(cNameFile, cNameFile4d);
    pfFile[0] = fopen(cNameFile, "rb");
    strcpy(cNameFile, cNameFile5e);
    pfFile[1] = fopen(cNameFile, "rb");
    strcpy(cNameFile, cNameFile6f);
    pfFile[2] = fopen(cNameFile, "rb");

    for(i=0; i<5; i++) {
        fread(&iNums[i], 4, 1, pfFile[0]);
        printf("\n%d",iNums[i]);
    }
    for(i=5; i<10; i++) {
        fread(&iNums[i], 4, 1, pfFile[1]);
        printf("\n%d",iNums[i]);
    }
    for(i=10; i<15; i++) {
        fread(&iNums[i], 4, 1, pfFile[2]);
        printf("\n%d", iNums[i]);
    }

    iResultFclose = fclose(pfFile[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose(pfFile[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose(pfFile[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
}

/* Version with pointer to pointer. */
void fReadFile(FILE** pfFile[]) {
    int i = 0, j = 0;

    int iNums[15] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    int iNums2[15] = {5001, 5002, 5003, 5004, 5005, 2033, 2066, 2099, 2133, 2166, 3001, 3002, 3003, 3004, 3005};
    char cNameFile4d[32] = "myFile4d.dat", cNameFile5e[32] = "myFile5e.dat", cNameFile6f[32] = "myFile6f.dat";
    char cNameFile[32] = {" "};
    int iResultFclose = 0;

    for(i=0; i<5; i++) {
        fread(&iNums[i], 4, 1, (*pfFile)[0]);
        printf("\n%d",iNums[i]);
    }
    for(i=5; i<10; i++) {
        fread(&iNums[i], 4, 1, (*pfFile)[1]);
        printf("\n%d",iNums[i]);
    }
    for(i=10; i<15; i++) {
        fread(&iNums[i], 4, 1, (*pfFile)[2]);
        printf("\n%d", iNums[i]);
    }

    iResultFclose = fclose((*pfFile)[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose((*pfFile)[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 1.");
        iResultFclose = fclose((*pfFile)[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 2.");

    strcpy(cNameFile, cNameFile4d);
    (*pfFile)[0] = fopen(cNameFile, "wb");
    for(i=0; i<5; i++)
        fwrite(&iNums2[i], 4, 1, (*pfFile)[0]);
    strcpy(cNameFile, cNameFile5e);
    (*pfFile)[1] = fopen(cNameFile, "wb");
    for(i=5; i<10; i++)
        fwrite(&iNums2[i], 4, 1, (*pfFile)[1]);
    strcpy(cNameFile, cNameFile6f);
    (*pfFile)[2] = fopen(cNameFile, "wb");
    for(i=10; i<15; i++)
        fwrite(&iNums2[i], 4, 1, (*pfFile)[2]);

    iResultFclose = fclose((*pfFile)[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose((*pfFile)[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 1.");
    iResultFclose = fclose((*pfFile)[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 2.");

    strcpy(cNameFile, cNameFile4d);
    (*pfFile)[0] = fopen(cNameFile, "rb");
    strcpy(cNameFile, cNameFile5e);
    (*pfFile)[1] = fopen(cNameFile, "rb");
    strcpy(cNameFile, cNameFile6f);
    (*pfFile)[2] = fopen(cNameFile, "rb");

    for(i=0; i<5; i++) {
        fread(&iNums[i], 4, 1, (*pfFile)[0]);
        printf("\n%d",iNums[i]);
    }
    for(i=5; i<10; i++) {
        fread(&iNums[i], 4, 1, (*pfFile)[1]);
        printf("\n%d",iNums[i]);
    }
    for(i=10; i<15; i++) {
        fread(&iNums[i], 4, 1, (*pfFile)[2]);
        printf("\n%d", iNums[i]);
    }

    iResultFclose = fclose((*pfFile)[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose((*pfFile)[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose((*pfFile)[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
}

/* Version without "&" in the caller. */
void fOptions(FILE* pfFileOpc[], int option) {
    int i = 0;
    switch (option)
    {
        case 1: {fReadFile(pfFileOpc); break;}
        case 2: {printf("\nHello!\n"); break;}
        default: break;
    }
}

/* Version with "&" in the caller. */
void fOptions(FILE* pfFileOpc[], int option) {
    int i = 0;
    switch (option)
    {
        case 1: {fReadFile(&pfFileOpc); break;}
        case 2: {printf("\nHello!\n"); break;}
        default: break;
    }
}

int main() {
    FILE *pFile[3];
    int i = 0, j = 0, option = 0, iResultFclose = 0;

    char cNameFile[32] = {" "};
    char cNameFile1a[32] = "myFile1a.dat", cNameFile2b[32] = "myFile2b.dat";
    char cNameFile3c[32] = "myFile3c.dat", cNameFile4d[32] = "myFile4d.dat";
    char cNameFile5e[32] = "myFile5e.dat",  cNameFile6f[32] = "myFile6f.dat";

    int iNums[15] = {2001, 2002, 2003, 2004, 2005, 2033, 2066, 2099,  2133, 2166, 3001, 3002, 3003, 3004, 3005};
    int iNums2[15] = {5001, 5002, 5003, 5004, 5005, 2033, 2066, 2099,  2133, 2166, 3001, 3002, 3003, 3004, 3005};

    strcpy(cNameFile, cNameFile1a);
    pFile[0] = fopen(cNameFile, "rb");
    if (!pFile[0])
        puts("Error opening the file1a");
    strcpy(cNameFile, cNameFile2b);
    pFile[1] = fopen(cNameFile, "rb");
    if (!pFile[1])
        puts("Error opening the file2b");
    strcpy(cNameFile, cNameFile3c);
    pFile[2] = fopen(cNameFile, "rb");
    if (!pFile[2])
        puts("Error opening the file3c");

    printf("\nWrite an option: \n");
    scanf("%d", &option);
    fOptions(pFile, option);

    puts("\n\nAnd we foooooolow....... \n\n");

    strcpy(cNameFile, cNameFile1a);
    pFile[0] = fopen(cNameFile, "rb");
    if (!pFile[0])
        puts("Error opening the file1a");
    strcpy(cNameFile, cNameFile2b);
    pFile[1] = fopen(cNameFile, "rb");
    if (!pFile[1])
        puts("Error opening the file2b");
    strcpy(cNameFile, cNameFile3c);
    pFile[2] = fopen(cNameFile, "rb");
    if (!pFile[2])
        puts("Error opening the file3c");

    for(i=0; i<5; i++) {
        fread(&iNums[i], 4, 1, pFile[0]);
        printf("\n%d",iNums[i]);
    }
    for(i=5; i<10; i++) {
        fread(&iNums[i], 4, 1, pFile[1]);
        printf("\n%d",iNums[i]);
    }
    for(i=10; i<15; i++) {
        fread(&iNums[i], 4, 1, pFile[2]);
        printf("\n%d", iNums[i]);
    }

    iResultFclose = fclose(pFile[0]);
    if (iResultFclose != 0)
        puts("Error closing the file 0.");
    iResultFclose = fclose(pFile[1]);
    if (iResultFclose != 0)
        puts("Error closing the file 1.");
    iResultFclose = fclose(pFile[2]);
    if (iResultFclose != 0)
        puts("Error closing the file 2.");

    return 0;
}

非常感谢。

Answer 1

单个文件句柄是指向FILE 的指针，即FILE *。由于您需要这些 FILE * 元素的数组，因此指向该数组的指针是 FILE **arr，相当于 FILE *arr[] 当用作函数的参数类型时。