本文通过一个简单的C语言程序示例，展示了不同数据类型间进行比较时可能遇到的问题。特别是当负数与无符号整数进行比较时，由于类型转换的原因可能会导致预期之外的结果。
猜猜下面代码的输出是什么？
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#include<stdio.h>
intarray[]=
{1,2,3,4,5,6,7,8,9,10};
#defineTOTAL_ELEMENTSsizeof(array)/sizeof(array[0])
intmain(){
intd=-1;
printf("d:%d\n",d);
if(d>TOTAL_ELEMENTS){
printf("d:%dd>TOTAL_ELEMENTS:%d\n",d,TOTAL_ELEMENTS);
}
if(d<(unsignedchar)1){
printf("d:%dd<unsignedchar1\n",d);
}
if(d>(unsignedint)1){
printf("d:%dd>unsignedint1",d);
}
getchar();
}
#include<stdio.h>intarray[]={1,2,3,4,5,6,7,8,9,10};#defineTOTAL_ELEMENTSsizeof(array)/sizeof(array[0])intmain(){intd=-1;printf("d:%d\n",d);if(d>TOTAL_ELEMENTS){printf("d:%dd>TOTAL_ELEMENTS:%d\n",d,TOTAL_ELEMENTS);}if(d<(unsignedchar)1){printf("d:%dd<unsignedchar1\n",d);}if(d>(unsignedint)1){printf("d:%dd>unsignedint1",d);}getchar();}
ANSI C编译器下的结果为：
d:-1
d:-1 d > TOTAL_ELEMENTS:10
d:-1 d < unsigned char 1
d:-1 d > unsigned int 1
知道静悄悄的改变发生在哪儿了么？ ;-)
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