Example 203 Commander Argument Types

Table of Contents

• Live Demo
• Quick Tip for Using String Arguments
• Whole Code

In the previous example, we mentioned that aside from int, there are also float and string(char*) argument types.

• The float type works just like int—nothing complicated there.
  
• The string type, however, requires a little extra care because we need a buffer to store the parsed text.
  

Here’s how to handle it:

// This buffer will hold the content of the string argument.
char stringBuffer[30];
 
// Create a positional argument.
Argument stringArg(args, 0);
 
// Check if the argument was parsed correctly. 
// If not, it may indicate that the buffer is too small.
if (!stringArg.parseString(stringBuffer)) {
    caller->print("Argument error! A string is required!");
    return false;
}

If parseString() returns true, that means:

• The argument was successfully parsed.
  
• The string fits in the buffer.
  

If it fails, the buffer might be too small, or the provided argument isn't a valid string.

This approach ensures that string arguments are safely stored and processed!

Live Demo

Quick Tip for Using String Arguments

Here’s a quick tip for handling string arguments as a user:

If you try the command:

upper hello

The result will be:

HELLO

But if you run:

upper hello bello

You’ll still get:

HELLO

Why? Because by default, command-line arguments are separated by spaces.

If your string contains spaces, you need to enclose it in quotation marks, just like in the C programming language.

For example:

upper "hello bello"

This will correctly return:

HELLO BELLO

This small trick helps ensure your full string argument is passed correctly!

Whole Code

/*
 * Created on Aug 10 2020
 *
 * Copyright (c) 2023 - Daniel Hajnal
 * hajnal.daniel96@gmail.com
 * This file is part of the Shellminator project.
 * Modified 2023.05.13
*/
 
#include "Shellminator.hpp"
#include "Shellminator-Commander-Interface.hpp"
#include "Commander-API.hpp"
#include "Commander-Arguments.hpp"
 
// We have to create an object from Commander class.
Commander commander;
 
bool upper_func( char *args, CommandCaller* caller );
bool area_func( char *args, CommandCaller* caller );
 
Commander::systemCommand_t API_tree[] = {
    systemCommand( "upper", "Replaces all characters in a string to upper-case.", upper_func ),
    systemCommand( "area", "Calculates the volume of two float numbers", area_func ),
};
 
// Create a ShellminatorCommanderInterface object, and initialize it to use Serial
ShellminatorCommanderInterface shell( &Serial );
 
// System init section.
void setup(){
 
    Serial.begin(115200);
 
    // Clear the terminal
    shell.clear();
 
    commander.attachDebugChannel( &Serial );
    commander.attachTree( API_tree );
    commander.init();
 
    shell.attachCommander( &commander );
 
    // Initialize shell object.
    shell.begin( "arnold" );
 
}
 
// Infinite loop.
void loop(){
 
    // Process the new data.
    shell.update();
 
}
 
bool upper_func(char *args, CommandCaller* caller ){
    // In case of a string argument, a buffer is needed.
    // This buffer will store the the extracted string.
    char stringBuffer[ 30 ];
 
    int i;
 
    // Create a positional argument.
    Argument stringArg( args, 0 );
 
    if( !stringArg.parseString( stringBuffer ) ){
        caller -> print( "Argument error! A string is required!" );
        return false;
    }
    
    for( i = 0; i < strlen( stringBuffer ); i++ ){
        stringBuffer[ i ] = toupper( stringBuffer[ i ] );
    }
 
    caller -> print( "Upper case string: " );
    caller -> println( stringBuffer );
    return true;
}
 
bool area_func(char *args, CommandCaller* caller ){
    float area;
    Argument a( args, 0 );
    Argument b( args, 1 );
 
    if( !( a.parseFloat() && b.parseFloat() ) ){
        caller -> print( "Argument error! Two float numbers are required, separated with a blank space.\r\n" );
        return false;
    }
    
    // Calculate the area.
    area = (float)a * (float)b;
    
    // Print out the result.
    caller -> print( (float)a );
    caller -> print( " * " );
    caller -> print( (float)b );
    caller -> print( " = " );
    caller -> println( area );
    return true;
}

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Commander Simple Arguments Example	Commander Position Independent Arguments Example