CSV Library in C

Author: amin tahmasebi Release Date: 2023 License: ISC License

Overview

This library provides a simple and efficient way to read, manipulate, and write CSV (Comma-Separated Values) files in C. It offers functions for creating and destroying CSV rows and files, reading and writing CSV files, and performing various operations like appending rows, inserting columns, and exporting data in JSON format.

Features

• Dynamic Memory Management: Automatically manages memory for CSV rows and files, resizing as needed.
• File Operations: Read from and write to CSV files with customizable delimiters.
• Data Manipulation: Append rows, insert columns, and access individual cells.
• Utility Functions: Includes functions for printing CSV files to the console, finding rows based on search terms, validating cell formats, and more.
• JSON Export: Ability to export CSV data to JSON format.

Installation

To use this library, include the csv.h header in your C project and compile the csv.c source file along with your project files.

Functions

• CSVRow* csv_row_create(): Create a new CSV row.
• void csv_row_destroy(CSVRow *row): Destroy a CSV row and free memory.
• void csv_row_append_cell(CSVRow *row, const char *value): Append a cell to a CSV row.
• char* csv_row_get_cell(const CSVRow *row, size_t index): Get a cell value from a CSV row.
• CsvFile* csv_file_create(char delimiter): Create a new CSV file structure.
• void csv_file_destroy(CsvFile *file): Destroy a CSV file structure and free memory.
• void csv_file_read(CsvFile *file, const char *filename): Read a CSV file.
• void csv_file_write(const CsvFile *file, const char *filename): Write to a CSV file.
• void csv_file_append_row(CsvFile *file, CSVRow *row): Append a row to a CSV file.
• CSVRow* csv_file_get_row(const CsvFile *file, size_t index): Get a row from a CSV file.
• void csv_file_remove_row(CsvFile *file, size_t index): Remove a row from a CSV file.
• Additional utility functions are provided for column insertion, JSON export, etc.

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Example 1

Below is a simple example of how to use this library to read a CSV file and print its contents:

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() {
    const char *filename = "./test.csv"; // Replace with your CSV file's path
    char delimiter = ','; // Specify the delimiter used in your CSV file
    CsvFile* myCSV = csv_file_create(delimiter);  // Create a new CsvFile instance

    csv_file_read(myCSV, filename); // Read the CSV file

    fmt_printf("Contents of the CSV file:\n"); // Print the contents of the CSV file
    csv_print(myCSV);

    csv_file_destroy(myCSV);
    return 0;
}

Example 2: Appending Rows to CSV

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() {
    CsvFile* csv = csv_file_create(',');
    CsvRow* newRow = csv_row_create();

    csv_row_append_cell(newRow, "New Cell 1");
    csv_row_append_cell(newRow, "New Cell 2");
    csv_row_append_cell(newRow, "سلول جدید 3");

    csv_file_append_row(csv, newRow); // Append the new row to the CSV file
    csv_file_write(csv, "sources/updated_file.csv");   // Write the updated CSV file to a new file

    csv_file_destroy(csv);
    return 0;
}

Example 2: Removing Rows from CSV

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() 
{
    CsvFile* csv = csv_file_create(',');

    csv_file_read(csv, "sources/test.csv"); // Read an existing CSV file
    csv_file_remove_row(csv, 1); // Remove the second row (index 1)
    csv_file_write(csv, "sources/reduced_file.csv"); // Write the updated CSV file to a new file

    // Clean up
    csv_file_destroy(csv);

    return 0;
}

Example 3: Exporting CSV to JSON

#include "csv/csv.h"
#include "fmt/fmt.h"
#include <stdlib.h>

int main() {
    CsvFile* csv = csv_file_create(',');

    if (csv) {
        csv_file_read(csv, "./test.csv");
        if (csv->size == 0) {
            fmt_fprintf(stderr, "Error: No data read from CSV file.\n");
            return -1;
        }
        else {
            char* json = csv_export_to_json(csv); // Export to JSON
            if (json) {
                fmt_printf("JSON Output:\n%s\n", json);
                free(json); // Remember to free the allocated memory for the JSON string
            }
            else {
                fprintf(stderr, "Error: Failed to export CSV to JSON.\n");
            }
        }
        csv_file_destroy(csv);
    }
    else {
        fprintf(stderr, "Error: Failed to create CSV structure.\n");
    } 
    return 0;
}

Example 4: Inserting Columns into CSV

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() {
    CsvFile* csv = csv_file_create(',');
    csv_file_read(csv, "./test.csv"); // Read an existing CSV file

    // Create a column to be inserted
    CsvRow* newColumn = csv_row_create();
    csv_row_append_cell(newColumn, "Column Header");
    csv_row_append_cell(newColumn, "Data 1");
    csv_row_append_cell(newColumn, "Data 2");
    // ... add more cells as needed

    csv_file_insert_column(csv, 2, newColumn);  // Insert the column at index 2
    csv_file_write(csv, "file_with_new_column.csv"); // Write the updated CSV file to a new file

    // Clean up
    csv_row_destroy(newColumn);
    csv_file_destroy(csv);
    return 0;
}

Example 5 : Concatenate two file

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() {
    CsvFile* file1 = csv_file_create(',');
    CsvFile* file2 = csv_file_create(',');

    csv_file_read(file1, "sources/test_10.csv"); // Read the first CSV file
    csv_file_read(file2, "sources/test_100.csv"); // Read the second CSV file

    csv_file_concatenate(file1, file2); // Join file2 rows to file1
    csv_file_write(file1, "sources/merged_file.csv"); // Write the merged data to a new CSV file

    csv_file_destroy(file1);
    csv_file_destroy(file2);
    return 0;
}

Example 6 : find value in rows

#include "csv/csv.h"
#include "fmt/fmt.h"
#include <stdlib.h>

int main() {
    CsvFile* csv = csv_file_create(',');
    csv_file_read(csv, "sources/test_10.csv"); // Read a CSV file

    const char* searchTerm = "Air"; // Define the search term
    CsvRow** foundRows = csv_file_find_rows(csv, searchTerm); // Search for rows

    // Print found rows
    for (size_t i = 0; foundRows[i] != NULL; i++){
        fmt_printf("Found Row %zu:\n", i);
        for (size_t j = 0; j < foundRows[i]->size; j++) {
            fmt_printf("%s ", foundRows[i]->cells[j]);
        }
        fmt_printf("\n");
    }

    csv_file_destroy(csv);
    return 0;
}

Example 7 : If the string from the cell can be converted to an integer and back to a string without changing its content, it's considered valid.

#include "csv/csv.h"
#include "fmt/fmt.h"
#include <stdlib.h> 
#include <string.h>

int main(){
    CsvFile* csv = csv_file_create(',');
    csv_file_read(csv, "sources/test_10.csv"); 

    // Iterate through each row in the CSV file
    for (size_t i = 0; i < csv->size; ++i) {
        CsvRow* row = csv_file_get_row(csv, i);
        if (row != NULL) {
            char* cell = csv_row_get_cell(row, 2); // Get the third cell (Quantity Ordered)
            int value = atoi(cell); // Attempt to convert the cell to an integer
            char *buffer = fmt_sprintf("%d", value);

            bool isValid = strcmp(buffer, cell) == 0;
            fmt_printf("Row %zu - Quantity Ordered '%s' is %s\n", i + 1, cell, isValid ? "valid" : "invalid");
            free(buffer);
        }
    }

    csv_file_destroy(csv);
    return 0;
}

Example 8 : Just how header work

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() {
    CsvFile* csv = csv_file_create(',');
    CsvRow* header = csv_row_create();
    
    csv_row_append_cell(header, "Column1");
    csv_row_append_cell(header, "Column2");
    csv_row_append_cell(header, "Column3");
    csv_file_set_header(csv, header);

    csv_file_read(csv, "sources/test_10.csv"); // Read an existing CSV file (excluding the header)
    
    CsvRow* retrievedHeader = csv_file_get_header(csv); // Get and print the header row
    fmt_printf("Header Row:\n");

    for (size_t i = 0; i < retrievedHeader->size; ++i) {
        fmt_printf("%s ", retrievedHeader->cells[i]);
    }
    fmt_printf("\n");

    csv_file_destroy(csv);
    return 0;
}

Example 9 : Finding cell value and convert it to Integer

#include "csv/csv.h"
#include "fmt/fmt.h"

int main()
{
    CsvFile* csv = csv_file_create(',');
    csv_file_read(csv, "sources/test_10.csv"); // Read a CSV file

    CSVRow* row = csv_file_get_row(csv, 2); // Get the third row (index 2)
    if (row != NULL)
    {
        int value = csv_row_get_cell_as_int(row, 0);  // Convert the value of the first cell to an integer
        fmt_printf("Value of the first cell in third row as integer: %d\n", value);
    }

    csv_file_destroy(csv);

    return 0;
}

Example 10 : Printgin CSV file to Console

#include "csv/csv.h"
#include "fmt/fmt.h"

int main() {
    CsvFile* csv = csv_file_create(',');

    csv_file_read(csv, "sources/test.csv");  // Read an existing CSV file
    csv_print(csv); // Print the contents of the CSV file to the console

    csv_file_destroy(csv); 
    return 0;
}

Example 11 : Using String lib with Csv

gcc -std=c11 -O3 -march=native -flto -funroll-loops -Wall -Wextra -pedantic -s -o main ./main.c .\string\string.c .\csv\csv.c

#include "csv/csv.h"
#include "string/string.h"
#include "fmt/fmt.h"
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

// Function to convert a string to uppercase using the String library
void to_uppercase(String *str) {
    char* data = (char*) malloc(string_length(str) * sizeof(char));
    if (!data) {
        perror("Can not allocate Memory");
        exit(-1);
    }

    for (size_t i = 0; i < string_length(str); ++i) {
        char ch = string_at(str, i); 
        data[i] = toupper(ch);
    }
    string_replace(str, string_c_str(str), data);
    free(data);
}

int main() {
    const char *input_filename = "sources/test_10.csv"; // Replace with your CSV file's path
    const char *output_filename = "sources/output.csv"; // Output CSV file's path
    char delimiter = ','; // Specify the delimiter used in your CSV file
    CsvFile* myCSV = csv_file_create(delimiter);

    csv_file_read(myCSV, input_filename);

    // Iterate through each row and cell
    for (size_t rowIndex = 0; rowIndex < myCSV->size; ++rowIndex)   {
        CsvRow* row = csv_file_get_row(myCSV, rowIndex);

        for (size_t cellIndex = 0; cellIndex < row->size; ++cellIndex) {
            char* cellValue = csv_row_get_cell(row, cellIndex);
            String* cellString = string_create(cellValue); // Create a String object from the cell value

            to_uppercase(cellString);   // Convert to uppercase and append text
            string_append(cellString, " MODIFIED");

            free(row->cells[cellIndex]); // Free the original cell value
            row->cells[cellIndex] = strdup(string_c_str(cellString));
            string_deallocate(cellString);  // Deallocate the String object
        }
    }

    csv_file_write(myCSV, output_filename); // Write the modified CSV to a new file
    csv_file_destroy(myCSV); 
    return 0;
}