One Dimensional Arrays

• A one dimensional array is a structured collection of components all of the same type that is given a single name. Each elements is accessed by an index that indicates the element's position within the collection.
  • Note Structure
  • Element
  • Index
  • Homogeneous
  • Position
• This is a new data structure, but we don't have to declare it.
• It is built into C/C++ (and most languages)
• type identifier[const int expression]
  • int ages[20];
  • float conversionFactors[LAST_PLANET];
  • PersonT travelers[MAX_PASSENGERS];
• NOTE the constant expression.
• THIS IS NOT LEGAL

• int i;
  cout << "Enter the number of people"
  cin >> i;
  
  PersonT people[i];
      

• Some compilers will allow this, some will even do it right!
• Initialization of an array at declaration is possible.
  • string names[] = {"Albus","Wulfric", "Brian", "Dumbledore"};
  • PlanetT destinations[] = {MARS, VENUS, Earth};
  • int primes[5]={2,3,5,7,11};
  • Note, this last version is not preferred, as it can lead to errors.
  • sizeof operator is probably useful here.
• Accessing elements
  • Elements are at locations 0 through size-1
  • So if we have int foo[10], there are 10 elements at positions 0 through 9
  • foo[3]=5 will assign a five to the fourth element of the array (at position 3)
  • y = foo[7] * 3 + 1 will take the value at position 7, multiply it by 3 add one and store the result in y.
  • foo[-1] and foo[10] are both array index out of bounds errors
  • The compiler does not catch these.
  • Nor does runtime, for quite a while.
  • segmentation fault
• Aggregate operations

  I/O	NO
  Assignment	NO
  Math	NO
  Comparison	NO
  Argument	By Reference Only
  Return	NO