Posted to tcl by oldlaptop at Tue Dec 30 00:12:35 GMT 2025view raw

  1. [Commentary: Much, much worse, for obvious reasons. I'm sure it would be very apologetic if I asked it why it forgot the braces, but that relies on me knowing more than a hypothetical real querent would.]
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  3. Why does this Tcl code not work? expr $a + b
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  5. ChatGPT said:
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  7. The reason your Tcl code doesn't work is that the expr command in Tcl is used to evaluate arithmetic expressions, but it expects actual values or variables, not variable names in the form of $a and b in this case.
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  9. In your expression:
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  11. expr $a + b
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  13. $a refers to the value stored in the variable a.
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  15. b is treated as a literal string, not as a variable.
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  17. To fix this, you need to dereference both a and b as variables. You should use $b instead of just b. Here's the corrected version of your code:
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  19. expr $a + $b
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  21. Now, it will correctly evaluate the sum of the values stored in a and b.
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  23. If a and b are not defined before you run the expr command, make sure to assign values to them:
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  25. set a 5
  26. set b 10
  27. expr $a + $b ;# This will return 15
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  29. Let me know if you need further clarification!

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