I have no idea what I am doing to get this error, or what it means.

clang -ggdb3 -O0 -std=c11 -Wall -Werror -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable -Wshadow helpers.c -lcrypt -lcs50 -lm -o helpers /usr/bin/../lib/gcc/x86_64-linux-gnu/7.4.0/../../../x86_64-linux-gnu/crt1.o: In function _start': (.text+0x20): undefined reference tomain' clang-7: error: linker command failed with exit code 1 (use -v to see invocation) : recipe for target 'helpers' failed make: *** [helpers] Error 1

  • what was the command that you issued to compile the program? Which pset is this (by name, not number?)
    – Cliff B
    Commented Mar 25, 2020 at 22:08
  • this is PSET4 the blur section. All I am trying to do get my code to compile. It is really weird, I can compile my code, then when I attempt to compile it again, this happens and I have changed absolutely nothing.
    – Pete
    Commented Mar 25, 2020 at 23:56
  • Sorry, I added the section, not the name. The name is filter.
    – Pete
    Commented Mar 26, 2020 at 0:03
  • I'll ask again. What was the EXACT command that you used? What did you enter on the command line????
    – Cliff B
    Commented Mar 26, 2020 at 3:11
  • My apologies, Cliff! I am new to all of this. I was trying to "Make Helpers" I see below that I shouldn't have done that. Thank you for your help!
    – Pete
    Commented Mar 26, 2020 at 15:33

1 Answer 1


Be sure to make filter to compile the filter program which will incorporate your helpers.c changes. Don't try to make helpers since helpers.c is not a complete C program (it has no main function).

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