程序代码：

DEFINE CLASS iptextbox as TextBox
    Height = 20
    InputMask = "###.###.###.###"
    Width = 114
    Name = "iptextbox"
    
    PROCEDURE init
        this.SelStart=0
        this.SelLength=3
    ENDPROC 
    
    PROCEDURE keypress
    LPARAMETERS nKeyCode, nShiftAltCtrl

    DO CASE 
        CASE nkeycode=32 OR nkeycode=9 OR nkeycode=46 OR nkeycode=13 &&space,tab,".",enter
            IF this.selstart>AT(".",this.value,3)
                IF nkeycode=32 OR nkeycode=46 OR nkeycode=13
                    NODEFAULT 
                    KEYBOARD '{TAB}'
                ENDIF     
            ELSE 
                NODEFAULT 
                ctext=SUBSTR(this.Value,1,this.selstart)
                ndot=OCCURS(".",ctext) &&有几个“.”
                IF !(this.SelStart=AT(".",this.value,ndot) AND nkeycode=46)
                    ndot=IIF(ndot=3,3,ndot+1)
                    ndotpos=AT(".",this.value,ndot)
                    this.SelStart=ndotpos
                    this.SelLength=3
                ENDIF     
            ENDIF
    
        CASE BETWEEN(nkeycode,48,57) &&0-9
            NODEFAULT 
            DODEFAULT()
*!*            上面2句必不可少，否则this.selstart的值不正确，这是通过下面这句代码发现的。
*!*            SET MESSAGE TO TRANSFORM(this.SelStart)) &&用来观察this.selstart的表现
            IF INLIST(this.SelStart,AT(".",this.Value,1),AT(".",this.Value,2),AT(".",this.Value,3))
                this.SelLength=3
            ENDIF 
    ENDCASE             
    ENDPROC 
    
    PROCEDURE valid
    n=ALINES(atemp,this.Value,5,".")
    IF n#4
        SET MESSAGE TO "每个地址段的值不能为空"
        RELEASE atemp
        RETURN .f.
    ELSE
        FOR i =1 TO ALEN(atemp)
            IF !BETWEEN(EVALUATE(atemp(i)),0,255)
                SET MESSAGE TO "无效的ip地址端值"+atemp(i)
                npos=AT(atemp(i),this.Value,1)-1
                this.SelStart=npos
                this.SelLength=3
                RELEASE atemp
                RETURN .f.
            ENDIF     
        ENDFOR    
    ENDIF 
    endproc          
ENDDEFINE 

[此贴子已经被作者于2025-10-6 21:41编辑过]