MIPS汇编字符串统计程序计数异常求助：数字、大小写等统计错误

你的程序所有统计项返回24，本质是每个字符都被无条件计入所有统计类别，加上输入字符串（含换行符）总长度刚好为24，所以所有计数器都等于总字符数。以下是具体错误点和修复后的完整代码：

核心错误点 #

• 计数器无条件递增：判断数字、小写、大写字母的逻辑中，计算出条件结果$t8后，没有根据$t8的值决定是否递增计数器，而是直接执行addi操作，导致所有字符都被计入对应类别。
• 空格判断逻辑错误：空格判断的beq指令后没有添加分支跳过非空格的情况，无论字符是否为空格，都会执行increment_space标签下的计数器递增操作，所有字符都被算作空格。
• 语法错误：
  • 数据段声明错误：.date应为.data，错误的段声明会导致变量无法正确寻址。
  • syscall指令语法错误：li $v0.8应为li $v0, 8，逗号被误写为点，导致字符串读取功能失效。
  • 跳转指令语法错误：j-loop应为j loop，连字符被误写为减号，导致循环无法正常跳转。
  • 指令格式不规范：多处li$v0缺少空格（如li$v0,4），虽部分汇编器兼容，但需修正为li $v0, 4的规范格式。

修复后的完整代码 #

.data
     prompt: .asciiz "Enter the string: "
     result: .asciiz "Entered string contains:\n"
     newline: .asciiz "\n"
     digits: .asciiz " digits"
     lowercase: .asciiz " lower case"
     uppercase: .asciiz " upper case"
     spaces: .asciiz " spaces"
     buffer: .space 256 # Buffer for the read string

.text
.globl main
main:
     # Printing the prompt
     li $v0, 4
     la $a0, prompt
     syscall

     # Read a string of characters
     li $v0, 8
     la $a0, buffer
     li $a1, 256
     syscall

     # Initialization of variables
     li $t0, 0 # Total character count
     li $t1, 0 # Number of digits
     li $t2, 0 # Lower case counter
     li $t3, 0 # Upper case counter
     li $t4, 0 # Space counter

     # String processing
     la $t5, buffer # Address of the first character
     lb $t6, ($t5) # Read the first character

loop:
     beqz $t6, done # Exit if null character encountered (end of string)

     addi $t0, $t0, 1 # Increment the counter of all characters

     # Check if a character is a number
     li $t7, 48 # '0' in ASCII
     li $t8, 58 # ':' in ASCII code - limit value
     slt $t9, $t6, $t8 # Is the character less than ':'?
     slt $t8, $t7, $t6 # Is '0' less than the character?
     and $t8, $t8, $t9 # Are both conditions met?
     beq $t8, 1, increment_digit # Increment only if condition is true
     j check_lowercase

increment_digit:
     addi $t1, $t1, 1

check_lowercase:
     # Check if a character is a lowercase letter
     li $t7, 97 # 'a' in ASCII
     li $t8, 123 # '{' in ASCII code - limit value
     slt $t9, $t6, $t8 # Is the character less than '{'?
     slt $t8, $t7, $t6 # Is 'a' less than the character?
     and $t8, $t8, $t9 # Are both conditions met?
     beq $t8, 1, increment_lowercase # Increment only if condition is true
     j check_uppercase

increment_lowercase:
     addi $t2, $t2, 1

check_uppercase:
     # Check if a character is an uppercase letter
     li $t7, 65 # 'A' in ASCII
     li $t8, 91 # '[' in ASCII code - limit value
     slt $t9, $t6, $t8 # Is the character less than '['?
     slt $t8, $t7, $t6 # Is 'A' less than the character?
     and $t8, $t8, $t9 # Are both conditions met?
     beq $t8, 1, increment_uppercase # Increment only if condition is true
     j check_space

increment_uppercase:
     addi $t3, $t3, 1

check_space:
     # Check if a character is a space
     li $t7, 32 # ASCII space
     beq $t6, $t7, increment_space # Increment space counter if character is a space
     j next_char

increment_space:
     addi $t4, $t4, 1

next_char:
     addi $t5, $t5, 1 # Go to next character
     lb $t6, ($t5) # Load next character
     j loop

done:
     # Displaying results
     li $v0, 4
     la $a0, result
     syscall

     # Display the number of all characters
     li $v0, 1
     move $a0, $t0
     syscall

     li $v0, 4
     la $a0, newline
     syscall

     # Display number of digits
     li $v0, 1
     move $a0, $t1
     syscall

     li $v0, 4
     la $a0, digits
     syscall

     li $v0, 4
     la $a0, newline
     syscall

     # Display the number of lowercase letters
     li $v0, 1
     move $a0, $t2
     syscall

     li $v0, 4
     la $a0, lowercase
     syscall

     li $v0, 4
     la $a0, newline
     syscall

     # Display the number of capital letters
     li $v0, 1
     move $a0, $t3
     syscall

     li $v0, 4
     la $a0, uppercase
     syscall

     li $v0, 4
     la $a0, newline
     syscall

     # Display the number of spaces
     li $v0, 1
     move $a0, $t4
     syscall

     li $v0, 4
     la $a0, spaces
     syscall

     li $v0, 10 # End of program
     syscall

修复说明 #

• 每个类别判断后，通过beq $t8, 1, increment_xxx指令，仅当条件满足时才跳转到对应计数器递增的标签，否则跳过。
• 空格判断后添加j next_char，非空格字符不会执行空格计数器递增。
• 修正所有语法错误，规范指令格式。
• 将buffer移到.data段内，确保变量正确分配内存。

内容的提问来源于stack exchange，提问作者Mikołaj K.