1樓：殺神一刀斬
private sub label2_click()const pi = 3.14159
dim r as single, i as single, s as single
r = inputbox("請輸入半徑:", "輸入半徑")i = 2 * pi * r
s = pi * r ^ 2
label2 = label2 & r
label3 = label3 + str(i)label4 = label4 + str(s)end sub
當然你要有四個label控制元件，第一個可以隨便設定，例如寫成「計算圓的周長與面積」
2樓：匿名使用者
private sub command1_click()dim bj as single
dim zz as single
dim mj as single
bj = csng(text1.text)if bj <= 0 then
msgbox "你的輸入有誤"
exit sub
end if
mj = 3.1415 * bj * bjmsgbox "面積是" & format(mj, "0.00")end sub
private sub command2_click()dim bj as single
dim zz as single
dim mj as single
bj = csng(text1.text)if bj <= 0 then
msgbox "你的輸入有誤"
exit sub
end if
zz = 2 * bj * 3.1415
msgbox "周長是" & format(zz, "0.00")end sub
vb 輸入半徑，計算圓周長和圓面積
3樓：匿名使用者
執行通過，希望對你有幫助。
private sub command1_click()dim r as double
r = val(text1.text)
c = 2 * 3.14 * r
s = 3.14 * r * r
print "周長c="; c; "面積s="; send sub
private sub form_load()me.show
text1.text = ""
msgbox "請輸入要計算的圓的半徑"
text1.setfocus
end sub
vb：輸入半徑，計算圓周長和圓面積。執行介面如下
4樓：匿名使用者
private sub command1_click()if not isnumeric(text1) thenmsgbox "***"
text1.setfocus
exit sub
end if
dim r as single
r = val(text1.text)
text2.text = 3.14 * r * rend sub
private sub command2_click()if not isnumeric(text2) thenmsgbox "***"
text2.setfocus
exit sub
end if
dim r as single
r = val(text1.text)
text3.text = 2 * 3.14 * rend sub
5樓：
不瞭解isnumeric,寫了個函式
private sub command1_click()dim r as single
if isval(trim(text1.text)) thenr = val(text1.text)
text2.text = 3.14 * r * relse
msgbox "input error"
text1.setfocus
end if
end sub
private sub command2_click()dim r as single
if isval(trim(text1.text)) thenr = val(text1.text)
text3.text = 2 * 3.14 * relse
msgbox "input error"
text1.setfocus
end if
end sub
function isval(str as string) as boolean
dim strcmp
dim i as integer
dim strtemp as stringstrcmp = "0123456789."
isval = true
for i = 1 to len(str)strtemp = mid(str, i, 1)if mid(str, i, 1) = "." and mid(str, i + 1, 1) = "" then
isval = false
exit function
end if
if instr(strcmp, strtemp) = 0 thenisval = false
exit function
end if
next
dim str1() as string
str1 = split(str)
if ubound(str1) > 0 thenisval = false
exit function
end if
end function
怎樣用vb計算圓的面積和周長
6樓：匿名使用者
就兩個公式嘛
圓的周長＝2×半徑×圓周率＝直徑×圓周率
即：圓的周長＝2πr 或πd
面積：s=πr² 或s=π(d/2)²
程式，自己弄一個textbox 1用來輸入圓的半徑textbox2用來顯示計算結果周長
textbox3用來顯示計算結果面積
新增兩個button1命名為計算圓的周長和麵積。
定義常量π，定義半徑r
然後在button1 事件中新增計算和顯示結果**即可。
public class form1
const p = 3.14
private sub button1_click(byval sender as system.object, byval e as system.eventargs) handles button1.
click
textbox2.clear() '清空以前計算結果textbox3.clear() '清空以前計算結果if textbox1.
text <> string.empty then '判斷是否輸入半徑
dim r as double = textbox1.text'上面是這兩部的合併 dim r as double' r=textbox1.text
textbox2.text = 2 * p * rtextbox3.text = p * r * relse
msgbox("請輸入圓的半徑")
end if
end sub
end class
如果沒有輸入半徑，提示輸入半徑
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