📝 Added sandbox (code sketchbook)

sandbox/atoi.c

@@ -0,0 +1,19 @@
+/* https://www.tutorialspoint.com/c_standard_library/c_function_atoi.htm */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main() {
+    int val;
+    char str[20];
+
+    strcpy(str, "98993489");
+    val = atoi(str);
+    printf("String value = %s, Int value = %d\n", str, val);
+
+    strcpy(str, "tutorialspoint.com");
+    val = atoi(str);
+    printf("String value = %s, Int value = %d\n", str, val);
+
+    return 0;
+}