Need a suggestion in handling a file in C

[Lost User]

Sir, how to make my code to search for a specific file like this code searches in the specific location.

search = fopen("C:\\Users\\User\\Desktop\\test.txt","r");

Then how to make this code to search in the whole C directory for the test file like this

search = fopen("C:\\test.txt","r");

Kindly help me with this.