data segment
    table db 30 dup(?)
    n dw 30
    char db ?
data ends
code segment
main proc far
   assume cs:code,ds:data
start:push ds
      xor ax,ax
      push ax
      mov ax,data 
      mov ds,ax
      mov si,0          ;地址指針
      mov cx,n                 
input:mov ah,1
      int 21h           ;從鍵盤(pán)接受一個(gè)字符
      mov table[si],al  ;將其存放在數(shù)組table中
      inc si
      loop input            

      mov dl,0dh
      mov ah,2
      int 21h
      mov dl,0ah
      int 21h          ;輸出換行回車(chē)符
      
find: mov ah,1
      int 21h           ;從鍵盤(pán)輸入字符char
      mov char,al
        
      mov dl,0dh        ;輸出換行回車(chē)
      mov ah,2
      int 21h
      mov dl,0ah
      int 21h
    
      mov dl,char       ;在下一行輸出字符char
      int 21h 

      call count        ;調(diào)用子程序count
      cmp dl,0          ;出口參數(shù)dl
      je exit           ;若字符串中無(wú)該字符,結(jié)束程序
      add dl,30h        ;否則將出現(xiàn)次數(shù)轉(zhuǎn)換成相應(yīng)的ASCII值
      cmp dl,39h
      jna output
      add dl,7
output:mov ah,2          ;輸出char在字符串中出現(xiàn)的次數(shù)
      int 21h
      jmp find
exit: ret
main endp
count proc near
      push si
      push cx
      push ax
      mov si,0
      mov cx,n
      mov al,char
c1:   cmp al,table[si]
      jne c2
      inc dl          ;dl是出口參數(shù),統(tǒng)計(jì)char在字符串中出現(xiàn)的次數(shù)
c2:   inc si  
      loop c1
      pop ax
      pop cx
      pop si
      ret
count endp
code ends
   end start