Bash function 与 printf Z78E6221F6393D1356681DB398F14CE6D 有时缺少

Question

I have a function that takes four parameters and outputs a formatted heading. Most of the time this function works, but occasionally it decides to not.

yelB=$'\e[1;33m'
fclr=$'\e[0m'

format_title() {
    # USAGE
    #   format_title "TITLE" "{h1/h2/h3}" "${color}" "{fill_character}"
    # EXMAPLE
    #   format_title "Heading 1" "h2" "$yelB" "="
    #   ============================ Heading 1 ============================

    ftitle=$1
    heading=$2
    color=$3
    fill=$4

    total_length=100
    ftitle_spacing=" "
    ftitle_border=$'\n' # variable implemented in h1 instances only
    formatted_ftitle=""

    if [[ $heading == "h1" ]]; then
        for (( i=1; i<=$total_length; i++ )); do
            ftitle_border=$ftitle_border$fill
        done
    fi

    if [[ $heading == "h1" || $heading == "h2" ]]; then
        ftitle_spacing="          "
    fi

    ftitle_fill=$(( ( $total_length / 2 ) - ( ${#ftitle} / 2 ) - ${#ftitle_spacing} ))

    for (( i=0; i<=$ftitle_fill; i++ )); do
        formatted_ftitle=$formatted_ftitle$fill

        if (( i == $ftitle_fill - 1 )); then

            formatted_ftitle=$formatted_ftitle$ftitle_spacing$color$ftitle$fclr$ftitle_spacing$formatted_ftitle

            # Check if the fill will be even or odd; if odd, remove the last fill character
            if (( $ftitle_fill % 2 )); then
                formatted_ftitle="${formatted_ftitle::-1}"
            fi

            if [[ $heading == "h1" ]]; then
                formatted_ftitle=$ftitle_border$'\n'$formatted_ftitle$ftitle_border$'\n'
            fi

            break
        fi
    done

    printf "%s\n" "$formatted_ftitle"
}

format_title "TEST HEADING ONE WITH EVEN NUMBER CHARACTERS" "h1" "$yelB" "#"
format_title "TEST HEADING TWO WITH ODD NUMBER CHARACTERS" "h1" "$yelB" "#"
format_title "TEST HEADING ONE WITH EVEN NUMBER CHARACTERS" "h2" "$yelB" "="
format_title "TEST HEADING TWO WITH ODD NUMBER CHARACTERS" "h2" "$yelB" "="
format_title "TEST HEADING ONE WITH EVEN NUMBER CHARACTERS" "h3" "$yelB" "-"
format_title "TEST HEADING TWO WITH ODD NUMBER CHARACTERS" "h3" "$yelB" "-"

Shell Output The idea is that all headings line up to a max of 100 characters with a fill character for titles with less than 100 characters.

As you can see, some headings don't line up; though trivial, it's very annoying (ignore the uncoloured heading -- a variable was misnamed when I printed the output).

I can't figure out what's causing the issue of some of the headings. Is it a character interpretation error with Bash when concatenating strings?

Answer 1

For h1/h2 you have ${#formatted_ftitle} = 18/19 for even/odd ${#ftitle} , respectively (ie, even=even, odd=odd).

But for h3 you have ${#formatted_ftitle} = 27/28 for even/odd ${#ftitle} , respectively (ie, odd=even, even=odd).

So, it looks like you need to take into consideration not only the odd/even-ness of the filler but also the title... when determining if you should strip off a trailing character.

Actually, it looks like it boils down to just having to worry about the even/odd-ness of ${#ftitle} , eg:

yelB=$'\e[1;33m'
fclr=$'\e[0m'

format_title() {
    # USAGE
    #   format_title "TITLE" "{h1/h2/h3}" "${color}" "{fill_character}"
    # EXMAPLE
    #   format_title "Heading 1" "h2" "$yelB" "="
    #   ============================ Heading 1 ============================

    ftitle=$1
    heading=$2
    color=$3
    fill=$4

    total_length=100
    ftitle_spacing=" "
    ftitle_border=$'\n' # variable implemented in h1 instances only
    formatted_ftitle=""

    if [[ $heading == "h1" ]]; then
        for (( i=1; i<=$total_length; i++ )); do
            ftitle_border=$ftitle_border$fill
        done
    fi

    if [[ $heading == "h1" || $heading == "h2" ]]; then
        ftitle_spacing="          "
    fi

    ftitle_fill=$(( ( $total_length / 2 ) - ( ${#ftitle} / 2 ) - ${#ftitle_spacing} ))

    for (( i=0; i<$ftitle_fill; i++ )); do
        formatted_ftitle=$formatted_ftitle$fill
    done

    formatted_ftitle=$formatted_ftitle$ftitle_spacing$color$ftitle$fclr$ftitle_spacing$formatted_ftitle

    # if the length of ftitle is odd, remove the last fill character

    if (( ${#ftitle} % 2 )); then
        formatted_ftitle="${formatted_ftitle::-1}"
    fi


    if [[ $heading == "h1" ]]; then
        formatted_ftitle=$ftitle_border$'\n'$formatted_ftitle$ftitle_border$'\n'
    fi

    printf "%s\n" "${formatted_ftitle}"
}

format_title "TEST HEADING ONE WITH EVEN NUMBER CHARACTERS" "h1" "$yelB" "#"
format_title "TEST HEADING TWO WITH ODD NUMBER CHARACTERS" "h1" "$yelB" "#"
format_title "TEST HEADING ONE WITH EVEN NUMBER CHARACTERS" "h2" "$yelB" "="
format_title "TEST HEADING TWO WITH ODD NUMBER CHARACTERS" "h2" "$yelB" "="
format_title "TEST HEADING ONE WITH EVEN NUMBER CHARACTERS" "h3" "$yelB" "-"
format_title "TEST HEADING TWO WITH ODD NUMBER CHARACTERS" "h3" "$yelB" "-"

####################################################################################################
##################          TEST HEADING ONE WITH EVEN NUMBER CHARACTERS          ##################
####################################################################################################


####################################################################################################
###################          TEST HEADING TWO WITH ODD NUMBER CHARACTERS          ##################
####################################################################################################

==================          TEST HEADING ONE WITH EVEN NUMBER CHARACTERS          ==================
===================          TEST HEADING TWO WITH ODD NUMBER CHARACTERS          ==================
--------------------------- TEST HEADING ONE WITH EVEN NUMBER CHARACTERS ---------------------------
---------------------------- TEST HEADING TWO WITH ODD NUMBER CHARACTERS ---------------------------