How to solve the Implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'int' warning?

Question

I am stuck with a warning on xcode, when I try to use the function of the tesseract package:

ocr->SetImage(im.data, im.cols, im.rows, 3, im.step);

I get a warning:

Implicit conversion loses integer precision: 'size_t' (aka 'unsigned long') to 'int'

How can I solve the problem?

That is a warning, not an error. And clearly you are passing an unsigned 32bit/64bit value where a signed 32bit value is expected, hence the potential loss of precision. Which input value is the `size_t` and which parameter is the `int`? — Remy Lebeau, Jan 23 '20 at 23:00
Just add a `static_cast(im.data)` (assuming it's `im.data` that's the 'offending' `size_t` argument). — Adrian Mole, Jan 23 '20 at 23:02

Yunus Temurlenk · Answer 1 · 2020-01-24T06:02:59.420

As documentation says:

Implicit conversions are automatically performed when a value is copied to a compatible type.

In your case, trying int to size_t is also an implicit conversion. The reason why the warning mentions about the precision:

According to these two differences between size_t and int, program assumes that some problems or precision loses can occur in the future.

In your case, you can simply convert your size_t type using static_cast conversion:

static_cast<int>(your_size_t_type_parameter)

Note: Using this method can eliminate your warning but this can cause some loses. For example if your size_t value is very huge.

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