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POGetting a glibc error when adding using pointers
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copied!<p>I have been getting the following error when I compile my program in terminal:</p> <pre><code>*** glibc detected *** ./a.out: double free or corruption (fasttop): 0x089660a0 *** ======= Backtrace: ========= /lib/i386-linux-gnu/libc.so.6(+0x6ebc2)[0xb7621bc2] /lib/i386-linux-gnu/libc.so.6(+0x6f862)[0xb7622862] /lib/i386-linux-gnu/libc.so.6(cfree+0x6d)[0xb762594d] ./a.out[0x8048668] ./a.out[0x8048fa3] /lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3)[0xb75cc113] ./a.out[0x80484c1] ======= Memory map: ======== 08048000-0804a000 r-xp 00000000 08:06 1835029 /home/fasih/poly/a.out 0804a000-0804b000 r--p 00001000 08:06 1835029 /home/fasih/poly/a.out 0804b000-0804c000 rw-p 00002000 08:06 1835029 /home/fasih/poly/a.out 08966000-08987000 rw-p 00000000 00:00 0 [heap] b7400000-b7421000 rw-p 00000000 00:00 0 b7421000-b7500000 ---p 00000000 00:00 0 b757f000-b759b000 r-xp 00000000 08:06 4195258 /lib/i386-linux-gnu/libgcc_s.so.1 b759b000-b759c000 r--p 0001b000 08:06 4195258 /lib/i386-linux-gnu/libgcc_s.so.1 b759c000-b759d000 rw-p 0001c000 08:06 4195258 /lib/i386-linux-gnu/libgcc_s.so.1 b75b1000-b75b3000 rw-p 00000000 00:00 0 b75b3000-b7729000 r-xp 00000000 08:06 4195237 /lib/i386-linux-gnu/libc-2.13.so b7729000-b772b000 r--p 00176000 08:06 4195237 /lib/i386-linux-gnu/libc-2.13.so b772b000-b772c000 rw-p 00178000 08:06 4195237 /lib/i386-linux-gnu/libc-2.13.so b772c000-b772f000 rw-p 00000000 00:00 0 b772f000-b7757000 r-xp 00000000 08:06 4195267 /lib/i386-linux-gnu/libm-2.13.so b7757000-b7758000 r--p 00028000 08:06 4195267 /lib/i386-linux-gnu/libm-2.13.so b7758000-b7759000 rw-p 00029000 08:06 4195267 /lib/i386-linux-gnu/libm-2.13.so b776c000-b776f000 rw-p 00000000 00:00 0 b776f000-b7770000 r-xp 00000000 00:00 0 [vdso] b7770000-b778e000 r-xp 00000000 08:06 4195224 /lib/i386-linux-gnu/ld-2.13.so b778e000-b778f000 r--p 0001d000 08:06 4195224 /lib/i386-linux-gnu/ld-2.13.so b778f000-b7790000 rw-p 0001e000 08:06 4195224 /lib/i386-linux-gnu/ld-2.13.so bfed6000-bfef7000 rw-p 00000000 00:00 0 [stack] Aborted </code></pre> <p>This is my code, it appears to be happening in the polyAdd function, but I also get an assertion fail in multiply so it could be both?</p> <pre><code> #include <stdio.h> #include <stdlib.h> #include <math.h> #include <stdbool.h> #include "poly.h" int polyDegree(struct poly *p) { return p->length-1; } struct poly *polyCreate() { struct poly *p = (struct poly *)malloc(sizeof(struct poly)); p->coeff=(double *)malloc(sizeof(double)); p->size=1; p->length=0; return p; } struct poly *polySetCoefficient (struct poly *p, int i, double value) { if(p == NULL) return; if(i>=p->size) { do { p->size = p->size*2; }while(i>=p->size); p->coeff = (double *)realloc(p->coeff, p->size*sizeof(double)); } while(i >= p->length) { p->coeff[p->length] = 0; p->length++; } p->coeff[i] = value; return p; } struct poly *polyDelete(struct poly *p) { if (p){ free(p);} return 0; } struct poly *polyCopy(struct poly *p) { struct poly *nP = polyCreate(); nP->size =p->size; nP->length = p->length; int i = 0; for (i = 0; i<(nP->size);i++) { nP->coeff[i] = p->coeff[i]; } return nP; } struct poly *polyAdd(struct poly *p0, struct poly *p1) { int i; struct poly *pF = polyCreate(); if (p0->length > p1->length) { pF = polyCopy(p0); for (i=0;i<p1->length;i++) pF->coeff[i] += p1->coeff[i]; } else if (p1->length >= p0->length) { pF = polyCopy(p1); for (i=0;i<p0->length;i++) pF->coeff[i] += p0->coeff[i]; } return pF; } struct poly *polyPrime (struct poly *p) { struct poly *pF = polyCreate(); pF->size = p->size; int i,j,k; int n = p->size; double a[n-1]; for (i = 1; i <=n;i++) { a[i-1] = i * p->coeff[i]; } for (i = 0; i < n; i++) { pF->coeff[i] = a[i]; } return pF; } struct poly *polyMultiply (struct poly *p0, struct poly *p1) { struct poly *product = polyCreate(); product->length = p0->length + p1->length - 1; product->size = p0->size + p1->size; product->coeff = (double *)malloc(product->size*sizeof(double)); int i,j; for(i=0;i<product->length;i++) product->coeff[i] = 0; for(i=0;i<p0->length;i++) for(j=0;j<p1->length;j++) product->coeff[i+j] += p0->coeff[i] * p1->coeff[j]; return product; } double polyGetCoefficient(struct poly *p, int i) { double val =p->coeff[i]; return val; } int checkZero (double a[], int n) { int x = 0; for (x = 0; x < n; x++) { if (a[x] != 0) return 1; } return 0; } double polyEval(struct poly *p, double x) { int i,n; double eval=0; if (!p) return 0; if (p) n = p->length; if (n == 0) return 0; for (i = 0; i<=n;i++) { if (p->coeff[i] == 0)continue; if (i == 0)eval += p->coeff[0]; else eval += p->coeff[i]* pow (x,i); } return eval; } void polyPrint (struct poly *p) { int x=0,y,z; int n; n = p->size; double a[p->size]; for (x = p->size; x >= 0; x--) { a[x] = p->coeff[x]; } bool check,neg,zero = true; if (!checkZero (a,n)) { printf("0\n"); } else{ for(x=(n-1);x>=0;x--) { check = false; neg = false; if (x < (n-1) && a[x+1] == 0 && a[x] != 0 && a[x] > 0 && !zero) printf(" + "); else if (x < (n-1) && a[x+1] == 0 && a[x] != 0 && a[x] < 0 && !zero) { printf (" - "); a[x] = a[x] * -1.00; } if (a[x] == 0) continue; if (a[x] != 0.0&& x > 1) { if (a[x] == -1)printf("-x^%d",x); else if (a[x] == 1)printf ("x^%d",x); else printf("%gx^%d",a[x],x); check = true;zero = false; } else if (x == 1) { if (a[x] == 1)printf("x"); else printf("%gx",a[x]); check = true; zero = false; } else if (x == 0) { printf("%g",a[x]); check = false; zero = false; } if (a[x-1] < 0 && x > 0){ printf (" - ");a[x-1] = a[x-1] * -1.00;} else if (x > 0&& a[x-1] != 0)printf(" + "); } printf("\n");} } </code></pre>

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