1.8 Arguments - Call by Value

• All functions arguments are passed "by value": called function is given the value of its arguments in temporary variables rather than originals
• Called function cannot directly alter a variable in the calling function
• Call by reference: the called routine has access to the original argument, not a local copy
• It is possible to arrange for a function to modify a variable in a calling routin. The caller must provide the address of the variable to be set (a pointer to the variable)
• The called function must declare the parameter to be a pointer.
• Call by value leads to more compact programs with fewer extraneous variables, because parameters can be treated as initialized local variables in the called routine
• To modify a variable in a calling function, the caller must provide the address of the variable to be set (pointer to the variable), and the called function must declare the parameter to be a pointer, and access the variable indirectly through it
• In contrast, when the name of an array is used as an argument in a calling function, the value passed to the calling function is the location or address of the beginning of the array - there is no copying of array elements
• By subscripting this value, the function can access and alter any element of the array