一、C语言if语句判断有符号int和无符合int 是否是true，会把有符号转成无符号。

二、实际C代码测试

      1、C代码

#include <stdlib.h>
 
int main()
{
    printf("Hello, World \r\n");
    
    int int_number = 0 ;
    
    if(int_number)
      printf("int_number=%d,int_number is true\r\n",int_number);
    else
      printf("int_number=%d,int_number is false\r\n",int_number);
    
    if(!int_number)
      printf("int_number=%d,!int_number is true\r\n",int_number);
    else
      printf("int_number=%d,!int_number is false\r\n",int_number);
    
    int_number =  -123 ;
    if(int_number)
      printf("int_number=%d,int_number is true\r\n",int_number);
    else
      printf("int_number=%d,int_number is false\r\n",int_number);
    if(!int_number)
      printf("int_number=%d,!int_number is true\r\n",int_number);
    else
      printf("int_number=%d,!int_number is false\r\n",int_number);
      
    int_number =  123 ;
    if(int_number)
      printf("int_number=%d,int_number is true\r\n",int_number);
    else
      printf("int_number=%d,int_number is false\r\n",int_number);
    
    if(!int_number)
      printf("int_number=%d,!int_number is true\r\n",int_number);
    else
      printf("int_number=%d,!int_number is false\r\n",int_number);
    
    
    unsigned int uint_value = 0;
    if(uint_value)
      printf("uint_value=%d,uint_value is true\r\n",uint_value);
    else
      printf("uint_value=%d,uint_value is false\r\n",uint_value);
    
    if(!uint_value)
      printf("uint_value=%d,!uint_value is true\r\n",uint_value);
    else
      printf("uint_value=%d,!uint_value is false\r\n",uint_value);
    
    uint_value = 126;
    if(uint_value)
      printf("uint_value=%d,uint_value is true\r\n",uint_value);
    else
      printf("uint_value=%d,uint_value is false\r\n",uint_value);
    
    if(!uint_value)
      printf("uint_value=%d,!uint_value is true\r\n",uint_value);
    else
      printf("uint_value=%d,!uint_value is false\r\n",uint_value);
    
    
    return(0);
}

      2、运行结果

标准输出：Hello, World 
int_number=0,int_number is false
int_number=0,!int_number is true
int_number=-123,int_number is true
int_number=-123,!int_number is false
int_number=123,int_number is true
int_number=123,!int_number is false
uint_value=0,uint_value is false
uint_value=0,!uint_value is true
uint_value=126,uint_value is true
uint_value=126,!uint_value is false