【C文件操作1】如何写入读取？fopen的6种组合参数怎么用？

/** @func:  fopen
*   @brief: 打开文件
*   @para:  [path]:文件路径，如："E:\Test\test.txt"
*           [mode]:文件打开方式（r w a r+ w+ a+ rb wb ab ...具体见下面表格）
*   @return:文件打开成功，则指向该流的文件指针就会被返回
*           文件打开失败，则返回NULL，并把错误代码存在errno中
*/
FILE * fopen(const char * path,const char * mode);

"r" = "rt", 因为默认打开text
"w" = "wt", 因为默认打开text
"a" = "at", 因为默认打开text
"r+" = "rt+", 因为默认打开text
"w+" = "wt+", 因为默认打开text
"a+" = "at+", 因为默认打开text

/** @func:  fread
*   @brief: 从文件读取
*   @para:  [buffer]:指向数据块的指针
*           [size]:每个数据的大小，单位为Byte(例如：sizeof(int)就是4)
*           [count]:数据个数
*           [stream]:文件指针，如fp
*   @return:实际读取的个数
*/
size_t fread(void *buffer, size_t size, size_t count, FILE *stream);

/** @func:  fwrite
*   @brief: 向文件写入
*   @para:  [buffer]:指向数据块的指针
*           [size]:每个数据的大小，单位为Byte(例如：sizeof(int)就是4)
*           [count]:数据个数
*           [stream]:文件指针，如fp
*   @return:实际写入的个数
*/
size_t fwrite(const void* buffer, size_t size, size_t count, FILE* stream);

/** @func:  fclose
*   @brief: 关闭文件
*   @para:  [stream]:文件指针，如fp
*   @return:关闭成功返回0，关闭失败返回EOF
*/
int fclose( FILE *stream );

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

#define DATA_SIZE 100
 
int main()
{
    unsigned char *pRawData = NULL;
    int *pData = NULL;
    
    /*使用malloc申请一块内存*/
    pRawData = (unsigned char *)malloc(sizeof(int) * DATA_SIZE);
    /*将该块内存强制转换为unsigned int*/
    pData = (int *) pRawData;
    
    /*对该块内存进行赋值 */
    int i = 0;
    for(i=0; i<DATA_SIZE; i++)
    {
        pData[i] = i; 
    }
    
    /*打开*/
    FILE *fp = fopen("../test1.bin","wb");
    if(NULL == fp)
    {
        printf("open file fail\r\n");
        goto end;
    }
    
    /*写入*/
    size_t cnt = fwrite(pData, sizeof(int), DATA_SIZE, fp);
    if(DATA_SIZE != cnt)
    {
        printf("write file fail\r\n");
        fclose(fp);
        goto end;
    }
    
    /*关闭*/
    fclose(fp);
    printf("file write ok\r\n");
    
 end:
    free(pRawData);/*malloc用完后要free*/
    system("pause");
    
    return 0;
}

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

#define DATA_SIZE 100
 
int main()
{
    int pData[DATA_SIZE];
    
    /*打开*/
    FILE *fp = fopen("../test1.bin","rb");/*写入的是bin, 读取的也必须是bin*/
    if(NULL == fp)
    {
        printf("open file fail\r\n");
        goto end;
    }
    
    /*读取*/
    size_t cnt = fread(pData, sizeof(int), DATA_SIZE, fp);
    if(DATA_SIZE != cnt)
    {
        printf("read file fail, read size:%d\r\n", cnt);
        fclose(fp);
        goto end;
    }
    printf("data[30]:%d\r\n", pData[30]);/*打印出其中一个数据*/
    
    /*关闭*/
    fclose(fp);
    printf("file read ok\r\n");
    
 end:
    system("pause");
    
    return 0;
}

/*定义结构体*/
typedef struct
{
	char name[256];
	unsigned int page;
	float price;	
}BOOK;
 
/*声明实例化一个结构体对象*/
BOOK book1 = {
    .name = "C语言基础",
    .page = 320,
    .price = 25.0,
};

/*打开*/
FILE *fp1 = fopen("../test2.bin","wb");
if(NULL == fp1)
{
    printf("open file fail\r\n");
    goto end;
}

/*写入*/
size_t cnt1 = fwrite(&book1, 1, sizeof(BOOK), fp1);
if(sizeof(BOOK) != cnt1)
{
    printf("write file fail\r\n");
    fclose(fp1);
    goto end;
}

/*打开*/
FILE *fp2 = fopen("../test2.bin","rb");
if(NULL == fp2)
{
    printf("open file fail\r\n");
    goto end;
}

/*读取*/
size_t cnt2 = fread(&myBook, 1, sizeof(BOOK), fp2);
if(sizeof(BOOK) != cnt2)
{
    printf("read file fail\r\n");
    fclose(fp2);    
    goto end;
}
printf("myBook info: name:%s, page:%d, price:%.2f\r\n",
       myBook.name, myBook.page, myBook.price);