英文:
Regular expression for 3 decimal point in flutter
问题
我想要实现以下功能：
小数点前有3位数字，小数点后只有1位数字
（同时还要检查前3位数字不能以0开头）
- 正确：230.8，179.0，200.0等
- 不正确：012.4，002.5，12.，12.22，1.4，1.222
目前我有以下代码：
TextFormField(
focusNode: participantHeightFocus,
// inputFormatters: [FilteringTextInputFormatter.digitsOnly],
inputFormatters: [
FilteringTextInputFormatter.allow(
RegExp(r'^\d+\.?\d*$')),
],
validator: (value) {
if (value!.isEmpty) {
return "Height is required";
} else if (!RegExp(r'^\d+(\.\d+)').hasMatch(value)) {
return "Please enter the height in cm (e.g., 170.0 cm)";
}
return null;
},
controller: participantHeight,
onChanged: (_) => calculateBMIAndUpdate(),
decoration: InputDecoration(
hintText: "Participant Height (*)",
labelText: "Participant Height (*)",
labelStyle: const TextStyle(fontSize: 20),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(5)),
),
),
它会显示错误，但允许我在小数点前输入多个数字，小数点后输入多个数字，还允许我以0开头，这是错误的。
英文:
I want to achieve the following:
3 digits before decimal point and a single digit after it
( while it also checks that starting 3 digits that are added should not have 0 as the first digit )
- Correct: 230.8, 179.0, 200.0 etc
- Incorrect: 012.4, 002.5, 12. , 12.22, 1.4, 1.222
for now i have this
TextFormField(
focusNode: participantHeightFocus,
// inputFormatters: [FilteringTextInputFormatter.digitsOnly],
inputFormatters: [
FilteringTextInputFormatter.allow(
RegExp(r'^\d+\.?\d*$')),
],
validator: (value) {
if (value!.isEmpty) {
return "Height is required";
} else if (!RegExp(r'^\d+(\.\d+)').hasMatch(value)) {
return "Please enter the height in cm (e.g., 170.0 cm)";
}
return null;
},
controller: participantHeight,
onChanged: (_) => calculateBMIAndUpdate(),
decoration: InputDecoration(
hintText: "Participant Height (*)",
labelText: "Participant Height (*)",
labelStyle: const TextStyle(fontSize: 20),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(5)),
),
),
it displays error but lets me enter many digits before decimal and many digits after decimal and it also allows me to start my number with 0 which is wrong
答案1
得分: 0
r'^[1-9]\d{2}.\d$'
如果要使小数点和数字可选（例如，170.0也可以写成170），稍微调整一下：
r'^[1-9]\d{2}(.\d)?$'
解释：
- ^ 匹配字符串的开头
- [1-9] 匹配除了0以外的每个数字
- \d{2} 匹配两个数字
- .\d 匹配点和一个数字
- $ 匹配字符串的结尾
- (...)? 使括号内的表达式变成可选项
英文:
Try this one:
r'^[1-9]\d{2}\.\d$'
If you want the decimal point and digit to be optional (if e.g. 170.0 can also be written as 170), adjust it a little:
r'^[1-9]\d{2}(\.\d)?$'
Explanation:
- ^ matches the start of the string
- [1-9] matches every digit except 0
- \d{2} matches two digits
- \.\d matches the point and one digit
- $ matches the end of the string
- (...)? makes the expression inside the parantheses optional
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