使用正则表达式QRegExp,在Qt帮助文档中有详细使用说明。
1.限制普通输入
拿ip设置输入框为例：
在输入框所在界面构造函数中写入：
QRegExp regExp("[0-9.]{1,15}");
ui->lineEdit_ipv4_addr->setValidator(new QRegExpValidator(regExp,this));
ui->lineEdit_ipv4_netmask->setValidator(new QRegExpValidator(regExp,this));其中：
[0-9.]表示只允许0-9之间的数字和特殊符号.的输入，如果需要限制字母，则改为[a-zA-Z]即可。
{1,15}表示匹配1次，并且最多允许输入15个元素。
2.按照一定的格式限制输入
还是拿ip输入框为例：
要求输入类似192.168.1.1这种ip地址，并且点不用自己输入，直接显示在输入框，输入3个数字后自动跳转点后面继续输入：
QString ipRangeStr = "(?:[0-1]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])";//限制最大输入255
QRegExp ipRegex ("^" + ipRangeStr
+ "\\." + ipRangeStr
+ "\\." + ipRangeStr
+ "\\." + ipRangeStr + "$");
auto ipValidator = new QRegExpValidator(ipRegex,this);//检查其有效性
ui->lineEdit_ipv4_addr->setValidator(ipValidator);
ui->lineEdit_ipv4_addr->setInputMask("000.000.000.000");更多用法：
Character Meaning
A
ASCII alphabetic character required. A-Z, a-z.
a
ASCII alphabetic character permitted but not required.
N
ASCII alphanumeric character required. A-Z, a-z, 0-9.
n
ASCII alphanumeric character permitted but not required.
X
Any character required.
x
Any character permitted but not required.
9
ASCII digit required. 0-9.
0
ASCII digit permitted but not required.
D
ASCII digit required. 1-9.
d
ASCII digit permitted but not required (1-9).
#
ASCII digit or plus/minus sign permitted but not required.
H
Hexadecimal character required. A-F, a-f, 0-9.
h
Hexadecimal character permitted but not required.
B
Binary character required. 0-1.
b
Binary character permitted but not required.
>
All following alphabetic characters are uppercased.
<
All following alphabetic characters are lowercased.
!
Switch off case conversion.
\
Use \ to escape the special characters listed above to use them as separators.
只需在双引号中标明要用的格式
“000.000.000.000;”是一个IP地址
“HH:HH:HH:HH:HH:HH;0”是一个MAC地址。
“\\0\\xHHHH;0”是只允许输入一个16位的十六进制数。