What are the problems of using an elastic tape to measure the length of a wall?

By using a tape measure

You measure a pen using a ruler

you can measure code length using different techniques i.e Function Point, COCOMO...

Please measure the length of this hallway.

No. You can only measure a person's length using some sort of marked off stick or measuring tape. After you know the person's length, you can describe it in meters if you want to tell others about it.

You could measure the length or width of it but you would have a decimal. You should be using centimeters.

We can easliy measure the lenght of a pencil using a ruler.

The length of the river system means the continuous length of the river channel.The scale of measurement of the river length is done over 1000 km .

With a Ruler line, extending from one point to another with a ruler By distance and things like inches, feet, yards, miles, and kilometers.

The stem mostly being above the ground grows in length very rapidly. It is easy to measure stem length without harming the plant as such.

measuring devices different according to the parameter you want to measure. weight is measure using weighing balance temperature is measure using a thermometer, or thermistor. length is measured using ruler. and so on

the ruler was used to measure the length of my book.

Using the Metric System: meters, kilometers.

It is a measure of length or distance, using the old Imperial units.

Square meters are a measure of area, not length. Therefore you could use square meters to measure the area of a basketball court.