MIPS-将输入字符串与存储在内存中的一个字符串进行比较 [英] MIPS - compare input string to one stored in memory

问题描述

我有一个用MIPS编写的有效的字符串比较方法(用户从输入中对两个字符串进行逐位比较)，但是我正在尝试对其进行更新，以将第二个输入与我存储在内存中的一个输入进行比较. (如果这两个相等，我想在其他地方使用第一个字符串.)

I have a functioning string compare method written in MIPS (bit by bit comparison of two strings from an input by the user), but I'm trying to update it to compare the second input with one that I have stored in memory. (If those two are equal, I want to use the first string somewhere else).

但是，我遇到了一些问题.这是我的代码:

However, I'm running into some issues. Here's my code:

.data  
str1: .space 20  
str2: .space 20  
msg1:.asciiz "Please enter string (max 20 characters): "  
msg2: .asciiz "\n Please enter method (max 20 chars): "  
msg3:.asciiz "\nSAME"  
msg4:.asciiz "\nNOT SAME"  


.text
.globl main

main:  
    li $v0,4        #loads msg1  
    la $a0,msg1  
    syscall

    li $v0,8
    la $a0,str1
    addi $a1,$zero,20
    syscall          #got string to manipulate

    li $v0,4        #loads msg2
    la $a0,msg2
    syscall

    li $v0,8
    la $a0,str2
    addi $a1,$zero,20
    syscall         #got string method

        la $a0,str1             #pass address of str1  
    la $a1,str2         #pass address of str2  
    jal methodComp      #call methodComp  

    beq $v0,$zero,ok    #check result  
    li $v0,4
    la $a0,msg4
    syscall
    j exit
ok:  
    li $v0,4  
    la $a0,msg3  
    syscall  
exit:  
    li $v0,10  
    syscall  

methodComp:  
    add $t0,$zero,$zero  
    add $t1,$zero,$a0  
    add $t2,$zero,$a1  

loop:  
    lb $t3($t1)         #load a byte from each string  
    lb $t4($t2)  
    beqz $t3,checkt2    #str1 end  
    beqz $t4,missmatch  
    slt $t5,$t3,$t4     #compare two bytes  
    bnez $t5,missmatch  
    addi $t1,$t1,1      #t1 points to the next byte of str1  
    addi $t2,$t2,1  
    j loop  

missmatch:   
    addi $v0,$zero,1  
    j endfunction  
checkt2:  
    bnez $t4,missmatch  
    add $v0,$zero,$zero  

endfunction:  
    jr $ra

本质上，我希望做的是在开始时声明

Essentially, what I was hoping to do was declare at the beginnning

strToCompare: .asciiz "foo"

，然后更改我通过的地址str1的地址

and change where I pass the adress of str1 from

la $a0,str1             #pass address of str1 

到

la $a0,strToCompare       #pass address of strToCompare

有人知道为什么这行不通吗，或者有更好的方法来实现吗? 非常感谢，如果我的格式设置已关闭，对不起，这是我第一次发布.

Does anyone know why this would not work, or a better way to implement this? Thanks a bunch, sorry if my formatting is off, this is my first time posting.

推荐答案

您缺少输入法(用于从用户输入数据的系统调用)所添加的换行符(\ n).结尾. 您可以预处理输入字符串以删除该换行符，也可以将其添加到存储的字符串中. 后者很容易，只需更改

You are missing the line feed character (\n) that your input method (the system call you are using to input data from the user) is adding at the end. You can either preprocess your input string to remove that line feed or add it to your stored string. The latter is easy, just change

strToCompare: .asciiz "foo"

到

strToCompare: .asciiz "foo\n"

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