Question

我遇到的问题是找到一个函数，用于查找在我的程序中运行最重要的数字。这是我用来测试它的代码：

#include <stdio.h>

void msbFinder(unsigned int);

int main()
{
    unsigned int x;
    printf("Input hexadecimal: ");
    scanf("%x", x);
    unsigned int y;
    y = msbFinder(x);
    printf("Most significant bit: %x", y);
}

unsigned int msbFinder(unsigned int x) //--Finds most significant bit in unsigned integer
{
    unsigned int a; //--Declare int that will be manipulated
    a = x; //--Initialise equal to passed value
    a = a|a>>1;
    a = a|a>>2;
    a = a|a>>4;//--var is manipulated using shifts and &'s so every value at and beneath the MSB is set to 1
    a = a|a>>8;//--This function assumes we are using a 32 bit number for this manipulation
    a = a|a>>16;
    a = a & ((~a >> 1)^0x80000000);//--Invert the int, shift it right once, & it with the uninverted/unshifted value
    return (a);//--This leaves us with a mask that only has the MSB of our original passed value set to 1
}

我正在使用Qt Creator，错误是：

void value not ignored as it ought to be
    y = msbFinder(x);
        ^

和

conflicting types for 'msbFinder'
unsigned int msbFinder(unsigned int x)
             ^

我已经在线查看了解决方案，但是我看不到导致此函数调用失败的错误。如何修复语法以使此功能正常工作？

Answer 1

在前向声明中，函数类型为void -

void msbFinder(unsigned int);

在定义函数时，它被定义为 -

unsigned int msbFinder(unsigned int x)   /*  <-- type given as unsigned int  */

您需要将前向声明中的函数类型更改为unsigned int。

Answer 2

文件顶部的声明说：

void msbFinder(unsigned int);

函数定义说：

unsigned int msbFinder(unsigned int x)

您是否看到void和unsigned int之间的区别？声明需要与定义相匹配。

函数中的冲突类型错误 - C.

2 个答案: