Added some regex examples.

Makefile

@@ -12,7 +12,7 @@ CPPFLAGS=-Wall -g -std=c++0x -pthread
 # CXX=clang++
 # CPPFLAGS=-Wall -g -std=c++0x -stdlib=libc++ -L/opt/clang/lib -pthread
 
-all: auto constexpr ilists init init_new lambda loops thread thread2 tuple
+all: auto constexpr ilists init init_new lambda loops regex1 regex2 thread thread2 tuple
 
 run: all
 	./auto
@@ -25,7 +25,9 @@ run: all
 	./thread
 	./thread2
 	./tuple
+	echo "1 11 1.1 1.1E12 stephen" | ./regex2
+	echo "hello cruel 12 world 12.22. you are 12.12 awesome!!" | ./regex2
 
 
 clean:
-	@rm -vf auto constexpr ilists init init_new lambda loops thread thread2 tuple
+	@rm -vf auto constexpr core* ilists init init_new lambda loops regex1 regex2 thread thread2 tuple

regex1.cc

@@ -0,0 +1,28 @@
+// from https://github.com/sol-prog/regex_tutorial
+#include <iostream>
+#include <regex>
+#include <string>
+
+using namespace std;
+
+int main() {
+	string input;
+
+    // traditional pcre escape
+    regex int_re {"(\\+|-)?\\d+"};
+
+    // ecmascript
+	regex float_re {"((\\+|-)?[[:digit:]]+)(\\.(([[:digit:]]+)?))?((e|E)((\\+|-)?)[[:digit:]]+)?"};
+
+    while(cin >> input){
+        if (regex_match(input, int_re)) {
+			cout << "integer" << endl;
+        }
+        else if(regex_match(input, float_re)) {
+			cout << "float" << endl;
+        }
+		else {
+			cout << "nan" <<endl;
+		}
+	}
+}

regex2.cc

@@ -0,0 +1,28 @@
+#include <iostream>
+#include <string>
+#include <regex>
+
+using namespace std;
+
+int main()
+{
+    //This should match any real number
+    regex number {"((\\+|-)?[[:digit:]]+)(\\.(([[:digit:]]+)?))?((e|E)((\\+|-)?)[[:digit:]]+)?\\b"};
+    //This should match any word
+    regex word {"[[:alpha:]]+"};
+    regex space {"\\s+"};
+    string input, clean_words, clean_numbers;
+    //Replace with an empty string
+    const string format {""};
+
+    getline(cin,input);
+
+    //Split the input string in numbers and words
+    clean_numbers=regex_replace(input, number, format);
+    clean_words=regex_replace(input, word, format);
+
+    cout << clean_words << endl;
+    cout << clean_numbers << endl;
+    return 0;
+}
+