如何使用正则表达式查找特殊字符串之间的所有数字？

Question

Given a string: HelloWorld{12:777}ByeWorld{13:888}OkayWorld{14:999}

My desired output are:

12
13
14

How to write a pattern (in C++ or Java) to find all numbers between string " World{ " and " : "?

Answer 1

Use lookarounds or capturing group.

Pattern.compile("(?<=World\\{)[^:]*(?=:)");

or

Pattern.compile("\\bWorld\\{([^:]*):");

Answer 2

You can try this:

#include<iostream>
#include<string>
#include<string.h>
using namespace std;

int main(void)
{
    char ch[100];

    scanf("%s", ch);
    char *token;
    token = strtok(ch, "{");
    token = strtok(NULL, ":");
    cout<< token << endl;
    return 0;
}