“免费"的类型冲突 [英] Conflicting types for "free"

问题描述

我遇到了错误

免费"的类型冲突

Conflicting types for 'free'

在下面的free()函数调用中.

int main ( )
{
    char fx [] = "x^2+5*x-1";
    node * fxNode = buildTree(fx, sizeof(fx)/sizeof(char));
    printf(deriveFromTree(fxNode)); // Should print "2*x+5"
    free(fxNode);
    return 0;
}

不知道为什么.不知道这是否重要，但是最重要的是

Can't figure out why. Not sure if this matter, but what's above it is

#include <stdio.h>

char opstack [5] = {'+','-','*','^', '\0'};

unsigned short int lowerOpPrecedence ( char, char, char * );

int stringToUnsignedInt ( char *, unsigned int * );
int stringToDouble ( char * , double * );
unsigned short int stringCompare ( char * , char * );
void stringCopy ( char * , char * );

typedef struct treeNode
{
    char * fx;
    char * op;
    struct treeNode * gx;
    struct treeNode * hx;
} node;


unsigned short int getNodeState ( node * );
node * buildTree ( char *, int );
char * basicDerivative ( char * );
char * derivateFromTree ( node * );

及其下面是一堆函数实现.

and what's below it is a bunch of function implementations.

推荐答案

您需要添加#include <stdlib.h>为free()提供原型.

You need to add #include <stdlib.h> to provide the prototype for free().

此外，推荐的main()签名是int main (void).

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