Spaces to Tabs Converter

How it is calculated

The tool looks at each line separately and only at the spaces at its very start. With tab width w it counts the leading spaces n, then writes tabs = ⌊n ÷ w⌋ tab characters followed by n mod w spaces that are left over, and then the rest of the line unchanged. Spaces inside a line, after the first non-space character, are never touched. A line that already begins with a tab stops the count at that tab, so spaces after it stay as spaces. The width is rounded to a whole number and must be at least 1. The result reports how many tab characters were inserted and how many lines were read, where a trailing line break counts as one more (empty) line. Line endings in the output are always plain newlines.

Common mistakes

• Choosing a width that does not match the file. If the code was indented with 2 spaces and you convert at 4, a 2-space line gets no tab at all and a 6-space line gets one tab plus 2 spaces.
• Expecting the leftover spaces to disappear. Indentation that is not a multiple of the width keeps the extra spaces after the tabs, which can look misaligned; fix the odd lines first.
• Expecting spaces in the middle of a line to change. Alignment spaces between words or columns are deliberately left alone, only the start of each line is converted.
• Running it on a file that already mixes tabs and spaces. Spaces that come after a tab at the start of a line are not converted, so such lines stay mixed.
• Using it on formats that need spaces, such as YAML, or on Markdown where a code block counts indentation. Tabs may break them.