# Using println to insert string into table

**URL:** <https://discourse.julialang.org/t/using-println-to-insert-string-into-table/109069>\
**Category:** New to Julia\
**Tags:** strings\
**Created:** [January 21, 2024, 12:06pm UTC](https://discourse.julialang.org/t/using-println-to-insert-string-into-table/109069 "2024-01-21T12:06:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![keynescoefen](https://avatars.discourse-cdn.com/v4/letter/k/d2c977/32.png) [@keynescoefen](https://discourse.julialang.org/u/keynescoefen)\
**Post date:** [January 21, 2024, 12:06pm UTC](https://discourse.julialang.org/t/using-println-to-insert-string-into-table/109069/1 "2024-01-21T12:06:35Z")

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Hello!  
Can someone explain to me why the command in the second loop produces an error? My hunch is that somehow quotes “” are missing in the `println` statement.

The MWE is here:

```julia
results_all_models = DataFrame( Model = "Single Cycle",
                                ParameterName="Log-likelihood",
                                Value = 1400);

namevec = ["p 1", "p 2"];
values = [1, 2]

for ins in zip(namevec,values)
    push!(results_all_models,["Single Cycle", ins[1] ,ins[2]]);
end

for ins in zip(namevec,values)
    push!(results_all_models,["Single Cycle", println(ins[1],"_tstat"), ins[2]]);
end

```

and the error message is here:

```julia
p 1_tstat
p 2_tstat
p 1_tstat
┌ Error: Error adding value to column :ParameterName. Maybe you forgot passing `promote=true`?
└ @ DataFrames /Users/jerome/.julia/packages/DataFrames/58MUJ/src/dataframe/insertion.jl:697
MethodError: Cannot `convert` an object of type Nothing to an object of type String

```

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**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [January 21, 2024, 12:42pm UTC](https://discourse.julialang.org/t/using-println-to-insert-string-into-table/109069/2 "2024-01-21T12:42:52Z")

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`println` doesn’t return a string, it prints directly to stdout and returns `nothing`. Use `string(ins[1], "_tstat")` or `printf` from the `Printf` stdlib instead.

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**Author:** ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Post date:** [January 21, 2024, 1:02pm UTC](https://discourse.julialang.org/t/using-println-to-insert-string-into-table/109069/3 "2024-01-21T13:02:47Z")

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> [@Sukera](#):
>
> or `printf` from the `Printf` stdlib instead.

\*`@sprintf`

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**Author:** ![Sukera](https://avatars.discourse-cdn.com/v4/letter/s/ce7236/32.png) [@Sukera](https://discourse.julialang.org/u/Sukera)\
**Post date:** [January 21, 2024, 3:28pm UTC](https://discourse.julialang.org/t/using-println-to-insert-string-into-table/109069/4 "2024-01-21T15:28:44Z")

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Right, that’s a typo 😆 Thank you!