汇编小写字母转换为大写字母.doc

汇编小程序：小写字母转换成大写字母实验内容：接收键入字符（以CTRL-C为结束），将小写字母变为大写字母，并在屏幕上显示。DATAS SEGMENT MESSAGE DB Welcome to the system!,13,10,13,10 DB The function of the program is changing small letters to capital letters.,13,10 DB If you enter capital letters or numbers there will be no changes.,13,10,13,10 DB Please enter a string.,13,10,$ CR DB 13,10,$ ;回车换行 STRING DB 100 DB 0 DB 80 DUP(0) ;定义缓冲区 AGAIN DB Do you want to try again?(Y or N),13,10,$ ERROR DB ERROR!,13,10,Please enter the right commomds.,13,10,$ ;错误提示DATAS ENDSSTACKS SEGMENT DB 200 DUP(?)STACKS ENDSCODES SEGMENT ASSUME CS:CODES,DS:DATAS,SS:STACKSSTART:HEAD: MOV AX,DATAS MOV DS,AX LEA DX,MESSAGE ;输出提示语 MOV AH,09H INT 21H LEA DX,STRING MOV AH,0AH INT 21H ;把字符串输入到BUF区 LEA DX,CR MOV AH,09H INT 21H ;以上为回车换行 LEA SI,STRING+2 ;把字符串首地址存入BX MOV CL,STRING+1 ;把字符个数存CX MOV CH,0NEXT1: MOV DL,SI CMP DL,a JB NEXT2 CMP DL,z JA NEXT2 ;ASCII码小于a和大于z的跳过，其余的减32 SUB DL,20H ;大小写字母的ASCII码差32NEXT2: MOV AH,02H INT 21H INC SI ;BX自加，判断下一个字符 DEC CX ;CX自减，最终将是0 JNE NEXT1 ;CX非零时，跳回NEXT1 MOV DX,OFFSET CR ;输出回车换行 MOV AH,09H INT 21H JMP EXITOVERFLOW: ;错误提示LEA DX,CRMOV AH,09HINT 21HLEA DX,ERRORMOV AH,09HINT 21HEXIT: LEA DX,CR MOV AH,09H INT 21H LEA DX,AGAIN ;提示是否再试一次MOV AH,09HINT 21HMOV AH,01HINT 21HPUSH AXLEA DX,CR MOV AH,09H INT 21H POP AXCMP AL,YJZ HEADCMP AL,yJZ HEADCMP AL,NJZ OVERCMP AL,nJZ OVERJMP OVERFLOWOVER: M