High-level Programming Language (Pascal)

String Functions

• length (<InStr>)
  • return the length of a <InStr> (i.e. the number of characters in the string)
  • for example,
    
    

  　L := length ('computer studies'); {assign a value of 16 to L}
  　L := length (''); {assign a value of 0 to L}
  　L := length (' '); {assign a value of 1 to L}

• Concatenation
  • is a process of joining strings together to form a longer string
  • strings can be concatenated using the function concat or the concatenation operator (+)
  • for example,


　String1 := 'Pascal';
　String2 :='Programming';
　CombineString := concat (String1, String2);
　　{or CombineString := String1 + String2;}
　writeln (CombineString); {the output is PascalProgramming}

• copy (<InStr>,<Start>,<Size>)
  • returns a substring with the specified <Size> from the <InStr>,
  • beginning at position <Start>
  • for example,
    
    　copy ('A programming course', 3, 11); {returns the value programming}
    
    
    • if <Start> is larger than the length of the <InStr>, an empty string (i.e. null string) is returned
    • if <Size> goes beyond the end of the <InStr>, whatever is present is copied and returned

     

  Ordering functions

• ord (<Character>)
  • returns the ASCII value of a <Character>
  • for example,
    
    

    Character	ord (Character)
    'A'	65
    'Z'	90
    ' ' {a space}	32
    '2'	50
    '9'	57
    '' {Null string}	0

    
    
    
• chr (<Code>)
  • where <Code> is a non-negative integer
  • the inverse of the ord function
  • returns the ASCII character associated with <Code>
  • for example,
    
    

    Code	chr (Code)
    49	'1'
    50	'2'
    65	'A'
    66	'B'
    97	'a'