String

Overview

This API provides basic string manipulation functions, similar to those found in the C standard library.

• strcat: Concatenates two strings.
• strchr: Finds the first occurrence of a character in a string.
• strcmp: Compares two strings.
• strcpy: Copies a string.
• strlen: Returns the length of a string.

Methods

strcat

Concatenates the source string to the destination string.

extern "C"
char *strcat(char *dest, const char *src);

• Parameters:
  • dest: The destination string.
  • src: The source string.
• Returns: A pointer to the destination string.

Example:

char dest[50] = "Hello, ";
char src[] = "World!";
strcat(dest, src);
// dest now contains "Hello, World!"

strchr

Finds the first occurrence of a character in a string.

extern "C"
const char *strchr(const char *str, char c);

• Parameters:
  • str: The string to search.
  • c: The character to find.
• Returns: A pointer to the first occurrence of the character, or NULL if the character is not found.

Example:

const char str[] = "Hello, World!";
char c = 'W';
const char *p = strchr(str, c);
// p points to "World!"

strcmp

Compares two strings.

extern "C"
int strcmp(const char *str1, const char *str2);

• Parameters:
  • str1: The first string.
  • str2: The second string.
• Returns: An integer less than, equal to, or greater than zero if str1 is found, respectively, to be less than, to match, or be greater than str2.

Example:

const char str1[] = "Hello";
const char str2[] = "World";
int result = strcmp(str1, str2);
// result is negative because "Hello" is less than "World"

strcpy

Copies the source string to the destination string.

extern "C"
char *strcpy(char *destination, const char *source);

• Parameters:
  • destination: The destination string.
  • source: The source string.
• Returns: A pointer to the destination string.

Example:

char dest[50];
const char src[] = "Hello, World!";
strcpy(dest, src);
// dest now contains "Hello, World!"

strlen

Returns the length of a string.

extern "C"
int strlen(const char *str);

• Parameters:
  • str: The string to measure.
• Returns: The length of the string, excluding the null terminator.

Example:

const char str[] = "Hello, World!";
int length = strlen(str);
// length is 13

Usage

Concatenating Strings

#include <sdk/os/string.hpp>
#include <sdk/os/debug.hpp>
#include <sdk/os/lcd.hpp>

// Add headers and app definition here ...

int main() {
    calcInit(); // Initialize the screen

    char dest[50] = "Hello, ";
    const char *src = "World!";

    strcat(dest, src);

    Debug_Printf(0,0,false,0, "%s", dest); // Output: Hello, World!

    LCD_Refresh();
    calcEnd(); // Restore the screen to the initial state

    return 0;
}

Finding a Character in a String

#include <sdk/os/string.hpp>
#include <sdk/os/debug.hpp>
#include <sdk/os/lcd.hpp>

// Add headers and app definition here ...

int main() {
    calcInit(); // Initialize the screen

    const char *str = "Hello, World!";
    char c = 'W';

    const char *p = strchr(str, c);
    if (p) {
        Debug_Printf(0,0,false,0, "Character found: %c", *p); // Output: Character found: W
    } else {
        Debug_Printf(0,0,false,0, "Character not found");
    }

    LCD_Refresh();
    calcEnd(); // Restore the screen to the initial state

    return 0;
}

Comparing Strings

#include <sdk/os/string.hpp>
#include <sdk/os/debug.hpp>
#include <sdk/os/lcd.hpp>

// Add headers and app definition here ...

int main() {
    calcInit(); // Initialize the screen

    const char *str1 = "Hello";
    const char *str2 = "World";

    int result = strcmp(str1, str2);
    if (result < 0) {
        Debug_Printf(0,0,false,0, "str1 is less than str2\n");
    } else if (result == 0) {
        Debug_Printf(0,0,false,0, "str1 is equal to str2\n");
    } else {
        Debug_Printf(0,0,false,0, "str1 is greater than str2\n");
    }

    LCD_Refresh();
    calcEnd(); // Restore the screen to the initial state

    return 0;
}

Copying a String

#include <sdk/os/string.hpp>
#include <sdk/os/debug.hpp>
#include <sdk/os/lcd.hpp>

// Add headers and app definition here ...

int main() {
    calcInit(); // Initialize the screen

    char dest[50];
    const char *src = "Hello, World!";

    strcpy(dest, src);
    Debug_Printf(0,0,false,0, "%s\n", dest); // Output: Hello, World!

    LCD_Refresh();
    calcEnd(); // Restore the screen to the initial state

    return 0;
}

Getting the Length of a String

#include <sdk/os/string.hpp>
#include <sdk/os/debug.hpp>
#include <sdk/os/lcd.hpp>

// Add headers and app definition here ...

int main() {
    calcInit(); // Initialize the screen

    const char *str = "Hello, World!";

    int length = strlen(str);
    Debug_Printf(0,0,false,0, "Length of string: %d\n", length); // Output: Length of string: 13

    LCD_Refresh();
    calcEnd(); // Restore the screen to the initial state

    return 0;
}