extern_c.cpp

Author: keineahnung2345

extern_c.cpp

@@ -0,0 +1,45 @@
+#include <stdio.h>
+
+//https://stackoverflow.com/questions/1041866/what-is-the-effect-of-extern-c-in-c
+//https://stackoverflow.com/questions/25210629/what-does-this-nm-output-mean
+
+extern "C" void show(const char* s){
+    printf("%s\n", s);
+};
+
+//extern "C" suppresses mangling, so overloading can't be performed
+//error: conflicting declaration of C function ‘void show(double)’
+/*
+extern "C" void show(double d){
+    printf("%lf\n", d);
+};
+*/
+
+//without extern "C", we can do overloading
+void show(int i){
+    printf("%d\n", i);
+};
+
+void show(float f){
+    printf("%f\n", f);
+};
+  
+int main() 
+{ 
+    const char* s = "GeeksforGeeks";
+    int i = 3;
+    float f = 3.5;
+    show(s); 
+    show(i);
+    show(f);
+    return 0; 
+} 
+
+/*
+output from "nm a.out | grep show":
+00000000004005e6 T show
+0000000000400623 T _Z4showf
+0000000000400601 T _Z4showi
+
+We can see that the name of the function show declared using extern "C" is not mangled.
+*/