C語言 fread()用法及代碼示例

C 中的 fread() 函數

原型：

    size_t fread(void *buffer, size_t length, size_t count, FILE *filename);

參數：

    void *buffer, size_t length, size_t count, FILE *filename

返回類型：size_t

函數的使用：

函數 fread() 的原型為：

    size_t fread(void *buffer, size_t length, size_t count, FILE *filename);

在文件處理中，通過fread()函數，我們讀取count大小對象的數量length從輸入流filename到名為的數組buffer.它返回從文件中讀取的對象數。如果讀取的對象較少，或者EOF在此之前遇到它會報錯。

C 中的 fread() 示例

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

int main()
{
    FILE* f;
    //initialize the arr1 with values
    int arr1[5] = { 1, 2, 3, 4, 5 };
    int arr2[5];
    int i = 0;

    //open the file for write operation
    if ((f = fopen("includehelp.txt", "w")) == NULL) {
        //if the file does not exist print the string
        printf("Cannot open the file...");
        exit(1);
    }
    //write the values on the file
    if ((fwrite(arr1, sizeof(int), 5, f)) != 5) {
        printf("File write error....\n");
    }
    //close the file
    fclose(f);

    //open the file for read operation
    if ((f = fopen("includehelp.txt", "r")) == NULL) {
        //if the file does not exist print the string
        printf("Cannot open the file...");
        exit(1);
    }
    //read the values from the file and store it into the array
    if ((fread(arr2, sizeof(int), 5, f)) != 5) {
        printf("File write error....\n");
    }
    fclose(f);

    printf("The array content is-\n");
    for (i = 0; i < 5; i++) {
        printf("%d\n", arr2[i]);
    }

    return 0;
}

輸出

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