Question

MIPS programming question

Problem 1: Write a program that asks the user to input a string (or no more than 50 characters). Your program should then output the length of the string. The string length should be determined using a separate function strlen that will accept the address of the string and return its length. For the purposes of this exercise, the length of a string will be defined as the number of non-null and non-newline characters until either the null character (ASCII 0) or the newline character (ASCII 10) is encountered.

Answer 1

Program screen shot:

Sample output:

Program code to copy:

;Declare the program

section   .data

   ; Input the string from the user

   prompt: .asciiz "Enter a string: "

   str: .space 50

  

   ; Display the length of the string

   msg: .asciiz "The length of the string is "

; Declare the text

.text

; THe main function of the program

main:

   ; Prompt the user string

   la $a0, prompt

   li $v0, 4

   syscall

    

   ;Read out the input string

   la $a0, str

   li $a1, 50

   li $v0, 8

   syscall

   ; Find out the string length

   #call the function strlen, address of string is already in $a0, lenght returned in $t1

   jal strlen

   ;Display function is used to display the result of the string

   li $v0, 4  

   la $a0, msg

   syscall

   li $v0, 1

   move $a0, $t1

   syscall

   #exit

   li $v0, 10

   syscall

; create a string length function method

strlen:

; Initiliaze the counter with t1 to zero.

   move $t1, $zero

  

; create a loop

strlen_loop:

   ; got the result character into t0

   lb $t0, ($a0)  

  

   ; Verify that is null character or not

   beq $t0, 0, strlen_end

  

   ; THe new line verify

   beq $t0, '\n', strlen_end

  

   ; Increment the counter one by one

   addi $t1, $t1, 1

   addi $a0, $a0, 1

  

   ; end of the loop

   b strlen_loop

  

; end of the string length

strlen_end:

; return to the register

   jr $ra