Question

i’m looking to change the following code:

    x = 0;
            dx = (val - (x * x)) / (2.0 * x);
            x = x + dx;
            diff = val - (x * x);
            x = x;
return (x);

into:

VARIABLE_TO_MONITOR_x = 0;
                dx = (val - (VARIABLE_TO_MONITOR_x * VARIABLE_TO_MONITOR_x)) / (2.0 * VARIABLE_TO_MONITOR_x);
                VARIABLE_TO_MONITOR_x = VARIABLE_TO_MONITOR_x + dx;
                diff = val - (VARIABLE_TO_MONITOR_x * VARIABLE_TO_MONITOR_x);
                VARIABLE_TO_MONITOR_x = VARIABLE_TO_MONITOR_x;
    return (VARIABLE_TO_MONITOR_x);

currently i’m using:

strLine.matches("^.*(?<![a-zA-Z])" +variableN[1] + "(?![a-zA-Z]).*$")

but this returns the following:

    VARIABLE_TO_MONITOR_x = 0;
            dVARIABLE_TO_MONITOR_x = (val - (VARIABLE_TO_MONITOR_x * VARIABLE_TO_MONITOR_x)) / (2.0 * VARIABLE_TO_MONITOR_x);
            VARIABLE_TO_MONITOR_x = VARIABLE_TO_MONITOR_x + dVARIABLE_TO_MONITOR_x;
            diff = val - (VARIABLE_TO_MONITOR_x * VARIABLE_TO_MONITOR_x);
            VARIABLE_TO_MONITOR_x = VARIABLE_TO_MONITOR_x;
return (VARIABLE_TO_MONITOR_x);

how can i tweak this regex to to not catch instances that are not specifically the variable i am looking for? This catches instances where the variable is contained within another word…

any help would be greatly appreciated..

regex noob..

EDIT:
here is the code that replaces as well..

if (strLine.matches("^.*(?<![a-zA-Z])" + variableN[1] + "(?![a-zA-Z]).*$"))
{
    strLine = strLine.replace(variableN[1], VARIABLES + variableN[1]);
}

Answer 1

\b

This is a great time to use “word boundaries”!

strLine.split("\\b" +variableN[1] + "\\b");

will return an array of line pieces broken up by just your variable name exactly. “\b” matches the edge of a word.

You can then print it out a piece at a time using your new variable name to glue it together. Or better yet:

strLine.replaceAll("\\b" +variableN[1] + "\\b", "VARIABLE_TO_MONITOR_" + variableN[1]);

Will do all the replacement for you!