Xcode "fails with exit code 1"

I'm new to xcode, 13 years old, and it stopped compiling my code! I'm working in C++ command line. My first project worked fine, but when I tried to run a new project, the build failed (not from syntax errors or anything) and gave me this notification:

Ld /Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfrsz qr/Build/Products/Debug/Test2 normal x86_64

cd /Users/cal/Documents/Application-Specific/XCode/Test2

setenv MACOSX_DEPLOYMENT_TARGET 10.7

/Developer/usr/bin/clang++ -arch x86_64 -isysroot /Developer/SDKs/MacOSX10.7.sdk -L/Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfr szqr/Build/Products/Debug -F/Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfr szqr/Build/Products/Debug -filelist /Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfrsz qr/Build/Intermediates/Test2.build/Debug/Test2.build/Objects-normal/x86_64/Test2 .LinkFileList -mmacosx-version-min=10.7 -o /Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfrsz qr/Build/Products/Debug/Test2

ld: duplicate symbol _main in /Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfrsz qr/Build/Intermediates/Test2.build/Debug/Test2.build/Objects-normal/x86_64/File. o and /Users/cal/Library/Developer/Xcode/DerivedData/Test2-dddrxmdmqydygiejxapflqfrsz qr/Build/Intermediates/Test2.build/Debug/Test2.build/Objects-normal/x86_64/Calcu lator.o for architecture x86_64

Command /Developer/usr/bin/clang++ failed with exit code 1

I bolded the part that seemed most important. Did it lose a file? Even my earlier project, which worked fine, won't run anymore.

Please respond, because I'm brand new and this means I can't code anymore.

Thanks!