[英]C - memory realloc error
我是编程的新手,这是一个可以找出限制内所有素数的程序。 但是,出现错误提示:
Prime 2(1682,0x7fff76316310) malloc: *** error for object 0x1002000a0: incorrect checksum for freed object - object was probably modified after being freed.
*** set a breakpoint in malloc_error_break to debug'
另外,Xcode报告一个问题,提示“信号SIGABRT”。 我怀疑这与“重新分配”功能有关。 到底是什么问题以及如何修复代码? 谢谢!
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
const int unit=3;
unsigned long* expandMem(unsigned long *primePtr, unsigned long count){
unsigned long* newPtr=(unsigned long*)realloc(primePtr, (count+unit)*sizeof(unsigned long));
return newPtr;
}
int main(){
unsigned long limit;
unsigned long count=0;
unsigned long* primePtr=(unsigned long*)malloc(sizeof(unsigned long)*unit);
*primePtr=2;
printf("Input the upper limit >>> ");
scanf("%ld",&limit);
for (unsigned long int number=3; number<=limit; number+=2) {
bool isPrime=true;
for (unsigned long i=0; (*(primePtr+i))*(*(primePtr+i))<=number; i++) {
if (number%(*(primePtr+i))==0) {
isPrime=false;
break;
}
}
if (isPrime) {
count++;
*(primePtr+count)=number;
if (count%unit==2) {
primePtr=expandMem(primePtr, count);
}
}
}
for (unsigned long i=0; i<=count; i++) {
printf("%ld ",*(primePtr+i));
}
}
重新分配将只为2个新元素分配空间,但是您假定它为3个新元素分配空间。
建议的更改(在expandMem中):
unsigned long* newPtr=(unsigned long*)realloc(primePtr, (count+1+unit)*sizeof(unsigned long));
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