直接上代碼,廢話終結(jié)者。
沒有注釋的地方自己慢慢體會~
char *argv[] = {"hello", "world", "!"};
char *a = argv[0];
char *b = argv[0] + 1;
char *c = argv[0 + 1];
char *cc = argv[1];
char **d = argv;
char *e = *argv;//意義與argv[0]相同。都是取字符串?dāng)?shù)組的第0個(gè)位置的值。當(dāng)然,這個(gè)值只是一個(gè)字符串的指針。
char *f = *argv + 1;//意義與arv[0] + 1相同。都是取第0個(gè)位置的字符串char*的第1個(gè)位置起始后的剩余字符。
char g = **argv;
printf("a=%s,b=%s,c=%s,cc=%s,d=%p,e=%s,f=%s,g=%c\n", a, b, c, cc, d, e, f, g);
//輸出:a=hello,b=ello,c=world,cc=world,d=0x7ff7b992b740,e=hello,f=ello,g=h
unsigned long size1 = sizeof(argv);
unsigned long size2 = sizeof(argv[0]);
unsigned long size3 = sizeof(argv[1]);
unsigned long size4 = sizeof(*argv);
unsigned long size5 = sizeof(**argv);
unsigned long size6 = sizeof(*a);
unsigned long size7 = sizeof(&a);
printf("size1=%lu,size2=%lu,size3=%lu,size4=%lu,size5=%lu,size6=%lu,size7=%lu\n", size1, size2, size3, size4, size5,
size6, size7);
//輸出:size1=24,size2=8,size3=8,size4=8,size5=1,size6=1,size7=8
值得注意的是:上面定義的char *argv[] = {"hello", "world", "!"};為字面量定義,如果是這個(gè)argv是一個(gè)函數(shù)參數(shù),就不要用sizeof(argv)了,因?yàn)槿〉玫慕Y(jié)果永遠(yuǎn)是一個(gè)sizeof(char*)的值。切莫想通過sizeof求出它作為數(shù)組的長度!
比如這樣:
void fun(char *argv[]){
int argc = sizeof(argv)/sizeof(char*);
printf("argc=%d",argc);
}
int main(void){
char *argv[] = {"hello", "world", "!"};
fun(argv);//輸出:argc=1
}
那怎么辦呢?當(dāng)然是直接在函數(shù)中fun(int argc,char *argv[])直接加上int argc參數(shù)來指明char *argv[]的具體的個(gè)數(shù),你還記得C語言的main函數(shù)怎么定義的嗎?int main(int argc,char *argv[]){}?;蛘哂靡恍┢渌鹷orkaround,但此時(shí)你必須要明確你在干什么:
void fun(char *argv[]) {
int i = 0;
while (argv[i]) {
i++;
}
printf("i=%d", i);
}