Custom String Formatting#

Introduction #

String formatting in C++ for VEX IQ uses printf-style format specifiers to create strings that include variables, expressions, or values. This method uses format specifiers like %d, %f, %s, etc., to insert values into strings.

int x = 1;
int y = 5;

// Display the variables using format specifiers
Brain.Screen.print("Position: (%d, %d)", x, y);

// Display a calculation using format specifiers
Brain.Screen.print("Sum: %d", 5 + 3);

// Display the robot's battery capacity using format specifiers
Brain.Screen.print("Battery: %d%%", Brain.Battery.capacity());

Formatting Numbers – Insert values and expressions into a string.

%d – Formats integers.
%.xf – Sets the number of decimal places to show for floats.
%x – Formats a number as hexadecimal.
%c – Formats single characters.
%s – Formats C-style strings.

Combining Strings – Combine text and values.

strcat – Concatenate C-style strings manually.

Checking for Substrings – Test for presence or position of text.

strstr – Finds a substring within a string.

Escape Sequences – Format output with special characters.

\n – Adds a line break (new line).
\t – Adds a tab space between items.

Formatting Numbers #

C++ uses format specifiers to control how numbers and other data types appear in strings:

Integers #

%d formats integer values.

Usage:
%d

Parameters	Description
	This method has no parameters.

int count = 42;
Brain.Screen.print("Count: %d", count);
// Output: Count: 42

Fixed Decimal Places #

%.xf controls how many decimal places a floating-point number is displayed with.

Usage:
%.xf

Parameters	Description
`x`	The number of decimal places to show.

// Display pi with 2 decimal places
double pi = 3.1415926535;
Brain.Screen.print("Pi: %.2f", pi);
// Output: Pi: 3.14

Hexadecimal #

%x converts numbers to hexadecimal (lowercase) or %X for uppercase.

Usage:
%x or %X

Parameters	Description
	This method has no parameters.

// Convert 255 to hexadecimal
int number = 255;
Brain.Screen.print("Hex: %x", number);
// Output: Hex: ff

Brain.Screen.print("Hex: 0x%X", number);
// Output: Hex: 0xFF

Characters #

%c formats single characters.

Usage:
%c

Parameters	Description
	This method has no parameters.

char letter = 'A';
Brain.Screen.print("Letter: %c", letter);
// Output: Letter: A

Strings #

%s formats C-style strings (character arrays).

Usage:
%s

Parameters	Description
	This method has no parameters.

char message[] = "IQ";
Brain.Screen.print("Hello, %s", message);
// Output: Hello, IQ

Combining Strings #

strcat can combine two strings together.

Note: Make sure that the string has enough space reserved for the characters that are being appended or it may start writing into memory that belongs to other variables.

Usage:
strcat(string1, string2)

Parameters	Description
`string1`	The string to add onto. Must have space for the new text.
`string2`	The string you want to add.

char message[] = "Hello,";
strcat(message, " IQ");

Brain.Screen.print("%s", message);
// Output: Hello, IQ

Checking for Substrings #

strstr returns a pointer to the position of the first occurrence of a C-style string in another string.

Usage:
strstr(str, substring)

Parameters	Description
`str`	A pointer to the string being searched.
`substring`	The string to search for.

Returns: Pointer to the first occurrence, or NULL if not found.

char message[] = "Hey everyone!";
if (strstr(message, "Hey") != NULL) {
    Brain.Screen.print("Hello!");
}

Escape Sequences #

Escape sequences are special characters used inside strings to format text output.

New Line #

\n moves text to a new line when printing.

Note: This only works on the console. Text will not be sent to the console until a new line is started.

Parameters	Description
	This method has no parameters.

// Display text on two lines
printf("First line\nSecond line\n");

Tab Spacing #

\t inserts a tab space between words or numbers.

Note: This only works on the console. Text will not be sent to the console until a new line is started.

Parameters	Description
	This method has no parameters.

// Display the quantity of barrels with tab spacing
int quantity = 2;
printf("Barrels:\t%d", quantity);