C-IO

2020-11-18

方法一

void readFile(char *filename){
    FILE *fp;
    fp = fopen(filename,"r");
    if (NULL == fp){
        printf("open %s error\n",filename);
        return;
    }
    uint8_t *str = NULL;
    size_t calloc_size = 1024;
    str = (uint8_t *)calloc(1,1024);
    int c = getc(fp);
    int index = 0;
    while (c != EOF){
        printf("%d\t",c);
        if (index != 0 && index % 16 == 0){
            printf("\n");
        }
        if (index > calloc_size){
            uint8_t  *tmp = calloc(1, calloc_size * 2);
            memcpy(tmp, str, calloc_size);
            calloc_size *= 2;
            free(str);
            str = tmp;
        }
        *(str + index) = c;
        index ++;
        c = getc(fp);
    }
    printf("\n");
    printf("readsize: %d bytes\n", index);
    printf("callocsize: %ld bytes\n", calloc_size);
    printf("\n");
    printf("%s\n", str);
    free(str);
    fclose(fp);
}

方法二

void readFile2(char *filepath) {
    struct stat statbuf;
    stat(filepath, &statbuf);
    long size = statbuf.st_size;
    FILE *fp;
    fp = fopen(filepath, "r");
    if (NULL == fp) {
        printf("open %s error\n", filepath);
        return;
    }
    uint8_t *str = NULL;
    str = (uint8_t *)calloc(1, size);
    if (NULL == str){
        printf("calloc failed.\n");
        return;
    }
    int c = getc(fp);
    size_t index = 0;
    while (c != EOF){
        *(str + index) = c;
        index ++;
        c = getc(fp);
    }
    printf("%s\n",str);
    free(str);
    fclose(fp);
}

方法3

void readFile3(const char *filepath) {
    FILE *fp;
    fp = fopen(filepath, "r");
    if (NULL == fp) {
        printf("open %s failed.\n", filepath);
        return;
    }
    struct stat statbuf;
    stat(filepath, &statbuf);
    long size = statbuf.st_size;
    char *buf = calloc(1, size + 1);
    size_t read_size = 0;
    char *res = fgets(buf, size + 1,fp);
    while (res != NULL) {
        read_size += strlen(res);
        res = fgets(buf + read_size, (size + 1 - strlen(res)), fp );
        
    }
    printf("%s\n", buf);
    printf("filesize: %ld\n", size);
    printf("readsize: %ld\n", read_size);
}

写入文件

void writeFile(char *filepath, const uint8_t *data, size_t data_len) {
    FILE *fp;
    fp = fopen(filepath, "w");
    if (NULL == fp){
        printf("open %s failed.\n", filepath);
        return;
    }
    size_t input_size = 0;
    while (input_size < data_len) {
        int c = putc(*(data + input_size), fp);
        if (c == EOF) {
            printf("write finish...\n");
            break;
        }
        input_size++;
    }
    fclose(fp);
}

void writeStringToFile(const char *filepath, const char *data) {
    FILE *fp;
    fp = fopen(filepath, "w");
    if (NULL == fp) {
        printf("open %s failed.\n", filepath);
        return;
    }
    int ret = fputs(data, fp);
    if(EOF == ret) {
        printf("write string %s failed.\n", data);
        fclose(fp);
        return;
    }
    fclose(fp);
}

void writeStringToFile2(const char *filepath, const char *data) {
    FILE *fp;
    fp = fopen(filepath, "w");
    if (NULL == fp) {
        printf("open %s failed.\n", filepath);
        return;
    }
    int ret = fprintf(fp, "%s", data);
    if (EOF == ret) {
        printf("write %s failed.\n", data);
        fclose(fp);
        return;
    }
    fclose(fp);
}

结构体,数组读写

typedef struct data_s {
    int type;
    char *description;
    int num[10];
    char str[1000];
    struct data_s *next;
} data_t;

void writeStruct2File(const char *filename, const data_t *data, const size_t data_size){
    FILE *fp;
    fp = fopen(filename, "w");
    if (NULL == fp) {
        printf("open %s failed.\n", filename);
        return;
    }
    size_t write_size = fwrite(data, data_size, 1, fp);
    printf("write_size: %ld\n", write_size);
    fclose(fp);
}

void readStructfromFile(const char *filename, data_t *data, size_t data_size) {
    FILE *fp;
    fp = fopen(filename, "r");
    size_t read_size = fread(data, data_size, 1, fp);
    printf("read_size: %ld\n",read_size);
    fclose(fp);
}
int main() {
     data_t data;
    
    data_t *data2;
    data2 = calloc(1, sizeof(data_t));
    
    memset(&data, 0, sizeof(data));
    strcpy(data2->str, "NEW DATA STRUCT");
    
    
    data.type = 1000;
    data.description = calloc(1, 30);
    strcpy(data.description, "Hello World...");
    strcpy(data.str,"this is data.str");
    int num[10] = {1,2,3,4,5,6,7,8,8,9};
    memcpy(data.num, num, sizeof(num));
    data.next = data2;
    
    writeStruct2File("Hello.bin",&data, sizeof(data) + 30);
    free(data.description);
    
    memset(&data, 0, sizeof(data));
    readStructfromFile("Hello.bin", &data, sizeof(data) + 30);
    printf("read data:::\n");
    printf("data->type:%d\n", data.type);
    printf("data->description:%s\n", data.description);
    printf("data->num::\n");
    for (int i = 0;i < 10;i ++) {
        printf("data->num[%d]:%d\n", i, data.num[i]);
    }
    printf("data->str:%s\n",data.str);
    printf("data->next: %p\n",data.next);
    if (NULL != data.next){
        printf("data->next->str:%s\n", data.next->str);
    }
    printf("finish!!!!");
    printf("data struct size:%ld", sizeof(data_t));
    return 0;
}

输出:

write_size: 1
read_size: 1
read data:::
data->type:1000
data->description:
data->num::
data->num[0]:1
data->num[1]:2
data->num[2]:3
data->num[3]:4
data->num[4]:5
data->num[5]:6
data->num[6]:7
data->num[7]:8
data->num[8]:8
data->num[9]:9
data->str:this is data.str
data->next: 0x55fea235c260
data->next->str:NEW DATA STRUCT
finish!!!!data struct size:1064

生成的文件大小为:1094字节, 为sizeof(data_t)+ 30;使用calloc的申请的内存块不会被存储.