[C language] use of file read / write function

 Comprehensive description by character , Press the line , Block read / write mode .

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

void fileCharWrite() {
    
    FILE *file_write = fopen("./test01.txt", "w");
    if (!file_write) {
    
        //ERROR: No such file or directory
        perror("ERROR");
        return;
    }

    char ch = 'a';

    for (int i = 0; i < 5; ++i) {
    
        fputc(ch, file_write);
    }

    fclose(file_write);

}


void fileCharRead() {
    
    FILE *file_read = fopen("./test01.txt", "r");
    if (!file_read) {
    
        perror("ERROR");
        return;
    }

    // Note that this will reflect feof() The lag of , The final will be EOF Identifier assignment ch, Or it can be done after the assignment if Judge , avoid EOF
    // while(!feof(file_read))
    // {
    
    // char ch = fgetc(file_read);
    // printf("%c\n", ch);
    // }

    // The following methods can also be avoided 
    char ch;
    while ((ch = fgetc(file_read)) != EOF) {
    
        printf("%c\n", ch);
    }

    fclose(file_read);

}


// Press the line 
void fileLineReadWrite() {
    
    // Write 
    FILE *file_write = fopen("./test02.txt", "w");
    if (!file_write) {
    
        perror("ERROR");
        return;
    }

    char *arr[] = {
    
            " Hoe standing grain gradually pawning a midday \n",
            " Sweat dripping under the grass \n",
            " Who knows what's on the plate \n",
            " Every grain is hard \n"
    };

    for (int i = 0; i < sizeof(arr) / sizeof(arr[0]); ++i) {
    
        fputs(arr[i], file_write);
    }

    fclose(file_write);


    // read 
    FILE *file_read = fopen("./test02.txt", "r");
    if (!file_read) {
    
        perror("ERROR");
        return;
    }

    char temp[100] = {
    0};
    while (fgets(temp, 100, file_read)) {
    
        printf("%s", temp);
    }

    fclose(file_read);

}


// By block 
void fileBlockReadWrite() {
    
    // Write 
    FILE *file = fopen("./test03.txt", "w");
    if (!file) {
    
        perror("ERROR");
        return;
    }

    char *arr[] = {
    
            " Hoe standing grain gradually pawning a midday \n",
            " Sweat dripping under the grass \n",
            " Who knows what's on the plate \n",
            " Every grain is hard \n"
    };

    for (int i = 0; i < sizeof(arr) / sizeof(arr[0]); ++i) {
    
        fwrite(arr[i], strlen(arr[i]), 1, file);
    }

    fclose(file);


    // read 
    file = fopen("./test03.txt", "r");
    if (!file) {
    
        perror("ERROR");
        return;
    }

    char temp[100] = {
    0};
    while (fread(temp, strlen(arr[0]), 1, file)) {
    
        printf("%s", temp);
    }

    fclose(file);

}


void test() {
    
    //fileCharWrite();
    //fileCharRead();
    //fileLineReadWrite();
    fileBlockReadWrite();

}

int main(int argc, char const *argv[]) {
    
    test();
    return 0;
}