Task: Displaying the Length of a String

Navigate to tasks/string-print-len/support/.

The program print_string_len.asm displays the length of a string using the PRINTF32 macro. The calculation of the length of the mystring string occurs within the program (it is already implemented).

Implement the program to display the length of the string using the printf function.

At the end, you will have the length of the string displayed twice: initially with the PRINTF32 macro and then with the external function call printf.

NOTE: Consider that the printf call is of the form printf("String length is %u\n", len);. You need to construct the stack for this call.

The steps to follow are:

  1. Mark the symbol printf as external.
  2. Define the format string "String length is %u", 10, 0.
  3. Make the function call to printf, i.e.:
    1. Put the two arguments on the stack: the format string and the length.
    2. Call printf using call.
    3. Restore the stack.

The length of the string is found in the ecx register.

To test the implementation, enter the tests/ directory and run:

make check

In case of a correct solution, you will get an output such as:

./run_all_tests.sh
test_length_zero                 ........................ passed ...  20
test_length_small                ........................ passed ...  40
test_length_large                ........................ passed ...  40

Total:                                                           100/100

If you’re having trouble solving this exercise, go through this reading material.