C语言 在c中将bool结果打印为“false”或“true”的最佳方法？
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Best way to print the result of a bool as 'false' or 'true' in c?
提问by Piseagan
I have to write a program in which main calls other functions that test a series of number if any are less than a number, if all the series' numbers are between two limits, and if any are negative. My code returns the values of 1 for true and 0 for false, but the assignment asks that they be printed as 'true' or 'false'. I'm not sure how to get the bool answers to print as a string from printf. I used if (atl == false) printf("false"); in my at_least.c and in main.c, but it returns only a long string of true or false (ex: truetruetrue....). I'm not sure if that is the correct coding and I'm putting it in the wrong spot or there was some other code that I need to use.
我必须编写一个程序，其中 main 调用其他函数来测试一系列数字，如果有任何小于一个数字，如果所有系列的数字都在两个限制之间，如果有任何为负数。我的代码返回值 1 为真，0 为假，但赋值要求将它们打印为“真”或“假”。我不知道如何从 printf 中获取 bool 答案以作为字符串打印。我使用 if (atl == false) printf("false"); 在我的 at_least.c 和 main.c 中，但它只返回一长串真或假（例如：truetruetrue....）。我不确定这是否是正确的编码，我把它放在错误的地方，或者我需要使用其他一些代码。
This is my main.c:
这是我的 main.c：
#include "my.h"
int main (void)
{
int x;
int count = 0;
int sum = 0;
double average = 0.0;
int largest = INT_MIN;
int smallest = INT_MAX;
bool atlst = false;
bool bet = true;
bool neg = false;
int end;
while ((end = scanf("%d",&x)) != EOF)
{
sumall(x, &sum); //calling function sumall
count++;
larger_smaller(x, &largest, &smallest); //calling function larger_smaller
if (atlst == false)
at_least(x, &atlst); //calling function at_least if x < 50
if (bet == true)
between(x, &bet); //calling function between if x is between 30 and 40 (inclusive)
if (neg == false)
negative(x, &neg); //calling function negative if x < 0
}
average = (double) sum / count;
print(count, sum, average, largest, smallest, atlst, bet, neg);
return;
}
my results for a set of numbers:
我对一组数字的结果：
The number of integers is: 15
The sum is : 3844
The average is : 256.27
The largest is : 987
The smallest is : -28
At least one is < 50 : 1 //This needs to be true
All between 30 and 40 : 0 //This needs to be false
At least one is negative : 1 //This needs to be true
This is in C, which I can't seem to find much on.
这是在 C 中，我似乎找不到太多。
Thanks in advance for your help!
在此先感谢您的帮助！
ADDENDUM:
附录：
This is repeated from an answer below.
从下面的答案中重复了这一点。
This worked for the at_least and negative functions, but not for the between function. I have
这适用于 at_least 和负函数，但不适用于 between 函数。我有
void between(int x, bool* bet)
{
if (x >= LOWER && x <= UPPER)
*bet = false;
return;
}
as my code. I'm not sure what's wrong.
作为我的代码。我不确定出了什么问题。
回答by R.. GitHub STOP HELPING ICE
Alternate branchless version:
替代无分支版本：
"false (a > b) ? "True" : "False";
true"+6*x
回答by Mitch Wheat
You could use C's conditional (or ternary) operator :
您可以使用 C 的条件（或三元）运算符：
x ? "True" : "False" ;
or perhaps in your case:
或者在你的情况下：
#include <stdio.h>
#define BOOL_FMT(bool_expr) "%s=%s\n", #bool_expr, (bool_expr) ? "true" : "false"
int main(int iArgC, char ** ppszArgV)
{
int x = 0;
printf(BOOL_FMT(x));
int y = 1;
printf(BOOL_FMT(y));
return 0;
}
回答by Oscar Korz
x ? "true" : "false"
x ? "true" : "false"
The above expression returns a char *, thus you can use like this:
上面的表达式返回 a char *，因此您可以像这样使用：
puts(x ? "true" : "false");or
printf(" ... %s ... ", x ? "true" : "false");
puts(x ? "true" : "false");或者
printf(" ... %s ... ", x ? "true" : "false");
You may want to make a macro for this.
您可能想为此制作一个宏。
回答by alk
So what about this one:
那么这个呢：
x=false
y=true
This prints out the following:
这将打印出以下内容：
#include "strbool.h"
const char alx_strbool[2][6] = {"false", "true"};
const char alx_strBool[2][6] = {"False", "True"};
const char alx_strBOOL[2][6] = {"FALSE", "TRUE"};
Using this with type bool but int should work the same way.
将此与类型 bool 一起使用，但 int 应该以相同的方式工作。
回答by Cacahuete Frito
I have three arrays for that:
我有三个数组：
strbool.c:
strbool.c：
#pragma once
/* rename without alx_ prefix */
#if defined(ALX_NO_PREFIX)
#define strbool alx_strbool
#define strBool alx_strBool
#define strBOOL alx_strBOOL
#endif
extern const char alx_strbool[2][6];
extern const char alx_strBool[2][6];
extern const char alx_strBOOL[2][6];
strbool.h:
strbool.h：
#include <stdio.h>
#define ALX_NO_PREFIX
#include "strbool.h"
int main(void)
{
int var = 7;
printf("var is %s\n", strBool[!!var]);
return 0;
}
Disclaimer: The prefixes are necessary because names starting with strare reserved(actually, only strbool), but until they are actually used by C or POSIX, I will use the short version.
免责声明：前缀是必需的，因为以 开头的名称str是保留的（实际上，只有strbool），但是在 C 或 POSIX 实际使用它们之前，我将使用简短版本。
It's very simple to use them:
使用它们非常简单：
var is True
