Super Study Sheets _9

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GLOBAL REGENTS SUPER STUDY SHEETS _9 - PAGE 1 of 6 THIS IS GLOBAL REGENTS SUPER STUDY SHEET NUMBER NINE THE TOPICS OF STUDY IN THIS PACKET ARE: • THE RENAISSANCE - This topic is divided into four parts. This packet covers all four: 1) What Happened During the Renaissance? 2) Why Did the Renaissance begin in Italy? 3) Niccolò Machiavelli 4) The Printing Press • THE PROTESTANT REFORMATION AND THE COUNTER (CATHOLIC) REFORMATION • THE SCIENTIFIC REVOLUTION • THE SPANISH GOLDEN AGE

protestant reformation
reason for the success
value of human reasoning
super study sheets
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C++ Pointers and Strings

C++ Spring 2000Arrays

Pointers A pointer is a variableMEMORY Address that holds theaddress 0 of something else.1 2 int foo;foo 123 3 4 int *x; 5 foo = 123; 81345 x = &foo;x 3 81346 81347 C++ Spring 2000Arrays

int *x;  xis a pointer to an integer.  Youcan use the integer x points to in a C++ expression like this: “the int x points to” y = *x + 17;

*x = *x +1;

C++ Spring 2000Arrays

&foo In C++ you can get theaddressof a variable with the “&” operator. MEMORY int foo; Address 0 1 foo = 123;2 x = &foo;foo 123 3 4 5 means “the address of foo” &foo

C++ Spring 2000Arrays

Assigning a value to a dere erencedpointer A pointer must have a value before you can dereferenceit (follow the pointer).

int *x; *x=3;

int foo; int *x; x = &foo; *x=3;

C++ Spring 2000Arrays

Pointers to anything some x int int *x; int **y;some some y *intint

double *z;

some z double

C++ Spring 2000Arrays

Pointers and Arrays

 Anarray name is basically aconstpointer.  Youcan use the [] operator with a pointer:

int *x; is “the address of” int a[10];x a[2] x = &a[2]; for (inti=0;i<3;i++) x[i]++; is the same as x[i] a[i+2] C++ Spring 2000Arrays 7

Pointer arithmetic  Integermath operations can be used with pointers.  Ifyou increment a pointer, it will be increased by the size of whatever it points to. int *ptr = a; *(ptr+2) *(ptr+4) *ptr

a[0] a[1] a[2] a[3] a[4] int a[5]; C++ Spring 2000Arrays

printing an array

void print_array(int a[], int len) { for (int i=0;i<len;i++) cout << "[" << i << "] = " << a[i] << endl; }

void print_array(int *a, int len) { for (int i=0;i<len;i++) cout << "[" << i << "] = " << *a++ << endl; }

C++ Spring 2000Arrays

Passing pointers as parameters

void swap( int *x, int *y) { int tmp;

tmp = *x; *x = *y; *y = tmp; }

C++ Spring 2000Arrays

Pointer Parameters  Pointersare passed by value (the value of a pointer is the address it holds).

 Ifwe change what the pointer points to the caller will see the change.

 Ifwe change the pointer itself, the caller won't see the change (we get a copy of the pointer) C++ Spring 2000Arrays 11

C++ strings  Astringis anull terminatedarray of characters. – null terminated means there is a character at the end of the the array that has the value 0 (null).  Pointersare often used with strings: char *msg = “RPI”; msg 'R' 'P' 'I'0 C++ Spring 2000Arrays 12

String Manipulation Functions

 C++includes a library of string handling functions:

char * strcpy(char *dst, const char *src) char * strcat(char *dst, const char *src) lots more!

C++ Spring 2000Arrays

String Example - Count the chars

int count_string( char *s) { int n=0; while (*s) { n++; s++; } return(n); }

C++ Spring 2000Arrays

Another way int count_string( char *s) { char *ptr = s; while (*ptr) { ptr++; } return(ptr - s); }

C++ Spring 2000Arrays

Exercises (for those so inclined)

 Write strcpy  Writea function that compares 2 strings and returns ifthey are the same string, true if they are not. false  Writea function that removes all spaces from a string.

C++ Spring 2000Arrays

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