GH-217: String in C++

concepts/cpp/string/README.md

@@ -9,6 +9,7 @@ In competitive programming, programmers use strings or arrays to store and manip
 
 ```c++
 #include <iostream>
+#include <string>
 
 using namespace std;
 ```
@@ -129,6 +130,27 @@ cout << "After : " << s << endl;
     After : the cat sat on the mat
 
 
+**Letters & Numbers**: Check if characters in the string are letters or numbers
+
+You can use
+
+* [`isalpha()`](https://cplusplus.com/reference/cctype/isalpha/) function to check if a character is a letter
+* [`isdigit()`](https://cplusplus.com/reference/cctype/isdigit/) function to check if a character is a number 
+* [`isalnum()`](https://cplusplus.com/reference/cctype/isalnum/) function to check if a character is either a decimal digit or an uppercase or lowercase letter.
+
+
+```c++
+string s = "I have 2 dogs, a poodle named Max and a German Shepherd named 7h3o#d0r.";
+
+for(int i = 0; i < s.length(); i++) {
+    if(isalnum(s[i])) {
+        cout << s[i];
+    }
+}
+```
+
+    Ihave2dogsapoodlenamedMaxandaGermanShepherdnamed7h3od0r
+
 ## 🔗 Further Reading
 
 * [String (computer science)](https://en.wikipedia.org/wiki/String_(computer_science)), wikipedia

concepts/cpp/string/notebook.ipynb

@@ -25,7 +25,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": 3,
    "metadata": {
     "vscode": {
      "languageId": "cpp"
@@ -34,6 +34,7 @@
    "outputs": [],
    "source": [
     "#include <iostream>\n",
+    "#include <string>\n",
     "\n",
     "using namespace std;"
    ]
@@ -299,6 +300,46 @@
     "cout << \"After : \" << s << endl;"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "**Letters & Numbers**: Check if characters in the string are letters or numbers\n",
+    "\n",
+    "You can use\n",
+    "\n",
+    "* [`isalpha()`](https://cplusplus.com/reference/cctype/isalpha/) function to check if a character is a letter\n",
+    "* [`isdigit()`](https://cplusplus.com/reference/cctype/isdigit/) function to check if a character is a number \n",
+    "* [`isalnum()`](https://cplusplus.com/reference/cctype/isalnum/) function to check if a character is either a decimal digit or an uppercase or lowercase letter."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {
+    "vscode": {
+     "languageId": "cpp"
+    }
+   },
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Ihave2dogsapoodlenamedMaxandaGermanShepherdnamed7h3od0r"
+     ]
+    }
+   ],
+   "source": [
+    "string s = \"I have 2 dogs, a poodle named Max and a German Shepherd named 7h3o#d0r.\";\n",
+    "\n",
+    "for(int i = 0; i < s.length(); i++) {\n",
+    "    if(isalnum(s[i])) {\n",
+    "        cout << s[i];\n",
+    "    }\n",
+    "}"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},

concepts/general/string/README.md

@@ -20,8 +20,12 @@ Here are some basic operations that you can perform on strings:
 * Substring: Extract a portion of the string
 * Comparison: Compare two strings for equality
 * Reversal: Reverse the order of characters in the string
+
+More operations
+
 * Uppercase: Convert all characters in the string to uppercase
 * Lowercase: Convert all characters in the string to lowercase
+* Letters & Numbers: Check if characters in the string are letters or numbers
 
 ## 🔗 Further Reading