Kenhuang Academy
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      • C File I/O

      File I/O allows programs to read from and write to files.

      1. File Operations

      #include <stdio.h>

FILE *fp = fopen("file.txt", "r");  // open file
if (fp == NULL) {
    perror("Error opening file");
    return 1;
}

// Read/write operations
fclose(fp);  // close file

      2. File Modes

      • "r" - read
      • "w" - write (overwrite)
      • "a" - append
      • "r+" - read and write

      3. Reading Files

      char buffer[100];
while (fgets(buffer, sizeof(buffer), fp) != NULL) {
    printf("%s", buffer);
}

      4. Writing Files

      fprintf(fp, "Hello, World!\n");
fputs("Another line\n", fp);