C `stdio.h` Library: Essential Functions for Input and Output

The <stdio.h> library in C is crucial for handling input and output operations. It includes a variety of functions for reading from and writing to files, managing user input, and formatted string handling, making it fundamental for performing I/O tasks in C programming.

C `stdio.h` Library

The <stdio.h> header provides various functions for handling input and output operations, including reading from and writing to files, managing user input, and formatted string handling. These functions are fundamental for performing I/O tasks in C.

Common C `stdio` Functions

Here is a list of some common functions provided by the stdio.h library along with their descriptions:

Function	Description
`fclose()`	Closes a file.
`feof()`	Returns true when the file pointer reaches the end of the file.
`ferror()`	Returns true if a file operation encounters an error.
`fgetc()`	Reads and returns the next character from a file.
`fgets()`	Reads a line of text from a file.
`fopen()`	Opens a file and returns a pointer for file operations.
`fprintf()`	Writes a formatted string to a file.
`fputc()`	Writes a character to a file.
`fputs()`	Writes a string to a file.
`fread()`	Reads data from a file into a block of memory.
`fwrite()`	Writes data from memory to a file.
`getc()`	Equivalent to `fgetc()`.
`getchar()`	Reads a single character from user input.
`printf()`	Prints a formatted string to the console.
`putchar()`	Writes a character to the console.
`puts()`	Outputs a string to the console.
`remove()`	Deletes a file.
`rename()`	Renames a file.
`scanf()`	Reads formatted input from the user.
`sprintf()`	Writes a formatted string into a char array.

Example: Basic File Operations

Let's take a look at an example that demonstrates file operations using stdio.h. The program opens a file, writes to it, and then reads the content back:

Example: Writing to and Reading from a File


#include <stdio.h>

int main() {
    FILE *filePointer;
    
    // Open a file in write mode
    filePointer = fopen("example.txt", "w");
    if (filePointer == NULL) {
        printf("Error opening file!\n");
        return 1;
    }

    // Write to the file
    fprintf(filePointer, "Hello, File!\n");
    
    // Close the file
    fclose(filePointer);

    // Open the file in read mode
    filePointer = fopen("example.txt", "r");
    if (filePointer == NULL) {
        printf("Error opening file!\n");
        return 1;
    }

    // Read from the file and print to console
    char line[100];
    fgets(line, sizeof(line), filePointer);
    printf("File content: %s", line);
    
    // Close the file
    fclose(filePointer);

    return 0;
}

Output:

Output


File content: Hello, File!

This program creates a file named example.txt, writes "Hello, File!" into it, and then reads the content back from the file, printing it to the console.

C stdio.h Library: Essential Functions for Input and Output

C stdio.h Library

Common C stdio Functions