Created
November 25, 2022 18:39
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Pointer Arithmetic
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int main() | |
{ | |
/* ====================================================================== */ | |
/* Pointer Arithmetic */ | |
/* ====================================================================== */ | |
/* | |
int urn[3]; | |
int *ptr1, *ptr2 | |
Valid: | |
- ptr1++; | |
- ptr2 = ptr1 + 2; | |
- ptr2 = urn + 1; | |
Invalid: | |
- urn++; | |
- ptr2 = ptr2 + ptr1; | |
- ptr2 = urn * ptr1; | |
*/ | |
int arraySum(int arrat[], const int sizeOfArray); | |
int arraySumTwo(int arrat[], const int sizeOfArray); | |
char charArr[4] = {'a', 'b', 'c'}; | |
char *charPtr = charArr; | |
printf("charPtr #0 = %c\n", *charPtr); // a | |
printf("charPtr #1 = %c\n", *(charPtr + 1)); // b | |
printf("charPtr #2 = %c\n\n", *(charPtr + 2)); // c | |
// set values | |
*charPtr = 'd'; | |
*(charPtr + 1) = 'e'; | |
*(charPtr + 2) = 'f'; | |
printf( | |
"charPtr #0 = %c\n" | |
"charPtr #1 = %c\n" | |
"charPtr #2 = %c\n", | |
*charPtr, *(charPtr + 1), *(charPtr + 2) // d, e, f | |
); | |
int values[10] = {3, 7, -9, 3, 6, -1, 7, 9, 1, -5}; | |
int result = arraySumTwo(values, 10); | |
printf("The sum is %i\n", result); | |
return 0; | |
} | |
/** Adds all items of array together*/ | |
int arraySum(int array[], const int sizeOfArray) | |
{ | |
int sum = 0, *ptr; | |
// Cannot change what arrayEnd points to - const is more efficient for the compiler | |
int *const arrayEnd = array + sizeOfArray; // &arr + 10 = address of end of array | |
// ptr is a hexadecimal address | |
for (ptr = array; ptr < arrayEnd; ++ptr) | |
sum += *ptr; // dereference ptr's each item in the array value | |
return sum; | |
} | |
/** | |
* Adds all items of array together | |
* Cut down version, using a pointer to array syntax | |
*/ | |
int arraySumTwo(int *array, const int sizeOfArray) | |
{ | |
int sum = 0; | |
// Cannot change what arrayEnd points to - const is more efficient for the compiler | |
int *const arrayEnd = array + sizeOfArray; // &arr + 10 = address of end of array | |
// ptr is a hexadecimal address | |
for (; array < arrayEnd; ++array) | |
sum += *array; // dereference ptr's each item in the array value | |
return sum; | |
} | |
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