lets say I have an array decleared such as:
double numArray[15]={14.83,19.24,0.84,1.98,3.47,0,0,0,0,0,827.39,632. 85,471.38,0.04,4.83}
and also I have some pointers decleared such as:
double *first=numArray;
double *last=first+4;
double *front=first+10;
double *back=first+14;
now how would I add up elements 0-4 and add up the elements 10-14, and subtract the second list(elements 10-14) from the first list(elements 0-4).
Lots of different ways to do it but they should include loops, or better yet, a single loop. When you want a sum of numbers you need to initailaize a variable to zero:
int sum =0;
Than use this notation:
sum += *ptr;
The pointer is dereferenced and the sum is the running total. Could also be written as:
sum = sum + *ptr; //same thing
try this, you only need 1 pointer
Code:#include <stdio.h> int main() { double numarray[] = {14.83,19.24,0.84,1.98,3.47,0,0,0,0,0,827.39,632.85,471.38,0.04,4.83}; double *numarray_ptr, total = 0; int size, x; numarray_ptr = numarray; size = sizeof(numarray) / sizeof(double); for(x=0; x<size; x++) { if(x < 4 || x > 9) total += *numarray_ptr; numarray_ptr++; } printf("\nToatal of numbers is %.2f\n", total); return 0; }
Last edited by SPOOK; 10-14-2001 at 11:42 AM.
http://www.cprogramming.com/cboard/s...&threadid=3083
More clues required.
Code:#include <stdio.h> double sum_array_segment ( double *start, double *end ) { double res = 0.0; while ( start <= end ) {// everything between the end pointers res = res + *start; // add start++; // and move on } return res; } int main ( int argc, char *argv[] ) { double numArray[15]={14.83,19.24,0.84,1.98,3.47, 0,0,0,0,0, 827.39,632.85,471.38,0.04,4.83}; double *first=numArray; double *last=first+4; double *front=first+10; double *back=first+14; printf( "%f %f\n", sum_array_segment( first, last), sum_array_segment( front, back ) ); return 0; }
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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