/***********************  05-4-S.TXT  **************************
 ***********  Prof. Dr. B. Bartning  ***************************/


Hints to solve the exercise 05-4.CPP
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(a) Try to understand the program!
    -> Self!
    How does the program terminate converting the string?
    Does the null character have an effect?
    -> The program terminates with each character unequal decimal digit/space,
       so e. g. with a letter, point, or also null byte.

(b) Input also (e. g.) the numbers
      2 thousand million, 3 th.m., 4 th.m., 5 th.m. (digit + 9 zeros!).
    Effect? Why?
    -> 2 th.m. : possible
       3 th.m., 4 th.m.: negative value  ) because of range overflow,
       5 th.m.: different positive value ) see (3.21.b) and (1.44)

(c) What does the program output if there is at least one space
    before a number without sign?
    -> permissible
    What does happen if there is a number with sign AFTER
    one or several spaces?
    -> not allowed because after space(s) loop with check
       on decimal digits/space

    Alteration: an arbitrary number of leading spaces
    BEFORE an optional sign is to be allowed (within max chacters).
    -> Insert the following lines directly after "i = 0;"
          while (line[i]==' ') 
             ++i;

(d) Use a constant definition
      const ....;
    instead of the preprocessor directive for max.
    -> instaed of the line "#define max 80"
       the following definition: "const int max=80;"

(e) What does the program output when encountering an empty string
    (i. e. only pressing the enter key)?
    -> value zero (program termination because of zero byte)

    ADDITIONAL EXERCISE:
    Alteration: If encountering an empty string, the program is to
    output a defined value (instead of the above behavior). It should
    be possible to alter this value very conveniently (in the program
    code), therefore defining this value should be done with a
    constant definition.
    -> Many possibilities, for example:
       insert constant definition (e. g. before "main"):
            const int valEmpty=-1492; // ... or another value
       insert directly after the line "cin.getline(..);":
            if (line[0]=='\0') {
               sign = 1;  // necessary because output of "sign*value"
               value = valEmpty;
            }
            else {
              // and here insert the complete following program text
              // up to excluding the output "cout << ..."
            }

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