The UART1 Output window shows the results of the program. The code uses the printf() function to print out a variety of data types and data formats. We’ll break down the steps next.

Below is a table of the most commonly used control characters for the printf() function. Anywhere one of these characters is encountered after a ‘%’ within a string, they will be replaced by the formatted value of its respective argument from the list following the string. The arguments may be literals or variables.

Below is an explanation of each printf() statement from the Lab3.c source file.

a. printf("25 as decimal (d): %d\n", 25);
This statement prints out the value 25 as a decimal integer (%d). The output correctly displays “25”.

b. printf("'a' as character (c): %c\n", 'a');
This statement prints out the letter ‘a’ as a character (%c). The output correctly displays “a”.

c. printf("'a' as decimal (d): %d\n", 'a');
This statement prints out the letter ‘a’ as a decimal integer (%d). Instead of displaying “a”, the output displays the ASCII value of the character ‘a’, which is 97. This isn't necessarily incorrect as it will depend on what your code is trying to accomplish with the character or variable of type char.

d. printf("2.55 as float (f): %f\n", 2.55);
This statement prints out the value 2.55 as a floating point number (%f). The output correctly displays “2.550000”. It is possible to specify the number of digits that should be displayed, but this was left as the default of 6 digits after the decimal point. (Default may vary among compilers.)

e. printf("2.55 as decimal (d): %d\n", 2.55);
This statement prints out the value 2.55 as a decimal number (%d). The output incorrectly displays “16419”. Because floating point values such as 2.55 are stored using the IEEE-754 format, it needs to be properly decoded to retrieve the correct value. In this case, we are displaying a portion of the raw IEEE-754 encoded value.

f. printf("6.02e23 as exponent (e): %e\n", 6.02e23);
This statement prints out the value 6.02 x 1023 as a signed real decimal value with an exponent (%e). The output correctly displays “6.020000e+23”.

g. printf("6.02e23 as decimal (d): %d\n", 6.02e23);
This statement prints out the value 6.02 x 1023 as a decimal integer (%d). The output incorrectly displays “26366” which is part of the raw IEEE-754 encoded floating point number.

h. printf("'Microchip' as string (s): %s\n", "Microchip");
This statement prints out the text “Microchip” as a string (%s). The output correctly displays “Microchip”.

i. printf("'Microchip' as decimal (d): %d\n", "Microchip");
This statement prints out the text “Microchip” as a decimal integer (%d). The output incorrectly displays the value -24132.