Either make your friends download the runtime DLL (@Kay's answer), or compile the app with static linking.
In visual studio, go to Project tab -> properties - > configuration properties -> C/C++ -> Code Generation
on runtime library choose /MTd
for debug mode and /MT
for release mode.
This will cause the compiler to embed the runtime into the app. The executable will be significantly bigger, but it will run without any need of runtime dlls.
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