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POAdding double type arrays to a structure of undefined length arrays
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copied!<p>Say that I have the following arrays that I call in a function:</p> <pre><code> int n = 20; double x[] = { 0.003435700407453, 0.018014036361043, 0.043882785874337, 0.080441514088891, 0.126834046769925, 0.181973159636742, 0.244566499024586, 0.313146955642290, 0.386107074429177, 0.461736739433251, 0.538263260566749, 0.613892925570823, 0.686853044357710, 0.755433500975414, 0.818026840363258, 0.873165953230075, 0.919558485911109, 0.956117214125663, 0.981985963638957, 0.996564299592547 }; double w[] = { 0.008807003569576, 0.020300714900193, 0.031336024167055, 0.041638370788352, 0.050965059908620, 0.059097265980759, 0.065844319224588, 0.071048054659191, 0.074586493236302, 0.076376693565363, 0.076376693565363, 0.074586493236302, 0.071048054659191, 0.065844319224588, 0.059097265980759, 0.050965059908620, 0.041638370788352, 0.031336024167055, 0.020300714900193, 0.008807003569576 }; </code></pre> <p>I would like to return the int n and the two arrays. I can do this by using a structure which is easy if I know the length of array x and w. However, the function depending on the inputs can return an array x of length 2,4,6,15, etc and an array w of length 2,4,6,15, etc. I do not know the length of array w and x. </p> <p>I've created a structure:</p> <pre><code> struct quadpts{ //structure used to pass multiple values into roeFlux int n; //The specific heat ratio double *x; double *w; }; typedef struct quadpts Quadpts; </code></pre> <p>and used:</p> <pre><code>Quadpts qpt = (Quadpts) malloc(size(Quadpts)); </code></pre> <p>to assign the varied length values in array x and w. However, I realized that people were adding one value at a time in many of the examples I have seen and looked up. Is it possible to assign a whole array to a varied length array in a structure? Or am I limited to filling the array in the structure 1 by one. Can this be done using a for loop? If so, would I have to define </p> <pre><code>Quadpts qpt = (Quadpts) malloc(size(Quadpts)); </code></pre> <p>in a different way each time to account for the new addition to the structure array?</p> <p>Thank you for your help. I'm new at C and am limited to MATLAB knowledge. </p> <p>EDIT:</p> <p>I realized that I have problems with those big arrays. I'm using a switch case syntax in order to allocate different size arrays to the variable x and w. But I realized that I need to designate the size of those arrays to begin with and they will only be seen within the for loop. How can I make it such that the arrays are seen outside of for loops such that I can save them to the structures? The following is a shorten version of my code. I'm constantly getting error at double x[n] as previous definition was here or redefinition. </p> <pre><code>double quad1d(int pqOrder){ int n; switch(pqOrder) { case 1: n = 1; double x[n] = { 0.500000000000000 }; double w[n] = { 1.000000000000000}; break; case 3: // Order 3 Gauss-Legendre points n = 2; double x[n] = { 0.211324865405187, 0.788675134594813 }; double w[n] = { 0.500000000000000, 0.500000000000000 }; break; } int i; Quadpts * qpt = (Quadpts*)malloc(sizeof(Quadpts)); for (i=0; i<n; i++){ qpt->x = malloc(qpt->x_len * sizeof(double)); qpt->w = malloc(qpt->w_len * sizeof(double)); qpt.x=x[i]; qpt.w=w[i]; } return &(qpt[0]); </code></pre> <p>}</p>

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