# Qt：正则表达式判断字符串是否为数值

记录一下，利用正则表达式判断字符串是否为数值（匹配是否为整数，浮点数或者科学计数法数值）
参考博客

#include <QString>
#include <QDebug>
#include <iostream>
#include <QRegExp>

static bool isNumeric(QString str) {
    if (str.size()==0) {
        return false;
    }
    QRegExp regx("[+-]*\\d+\\.?\\d*[Ee]*[+-]*\\d+");

    bool isNumber = regx.exactMatch(str.trimmed());
    if (isNumber) {
        return isNumber;
    }
    regx.setPattern("^[-\\+]?[.\\d]*$");
    return regx.exactMatch(str.trimmed());
}


int main(){
    QStringList strs={"1E8","   -9.81  ","-9.81A","-A9.81","1.025e3"};
    for(auto str:strs){
        qDebug()<<str<<" "<<isNumeric(str)<<QString(str).toDouble();
    }
    return 0;
}

输出：

"1E8"   true 1e+08
"   -9.81  "   true -9.81
"-9.81A"   false 0
"-A9.81"   false 0
"1.025e3"   true 1025