linux%3c%3c特殊符号解释,有关scanf("%3c%2c")的问题

最新推荐文章于 2022-03-03 15:24:53 发布

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最新推荐文章于 2022-03-03 15:24:53 发布

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文章标签： linux%3c%3c特殊符号解释

本文通过几个具体的C语言程序示例，展示了如何利用scanf函数的不同格式字符串来读取固定数量的字符，并将它们存储到指定的内存位置。示例包括了对多个连续字符的读取，以及对特定字符位置的指定。

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man scanf

...

c Matches a sequence of width count characters (default 1); the

next pointer must be a pointer to char, and there must be enough

room for all the characters (no terminating NUL is added). The

usual skip of leading white space is suppressed. To skip white

space first, use an explicit space in the format.

----------

#include

typedef unsigned char BYTE;

void print_memory(BYTE *start, int size)

{

int i;

for(i = size - 1; i >= 0; --i)

{

printf("%p:%02x: %c\n",

start + i,

*(start + i),

*(start + i));

}

int main(void)

{

char a[] = "XXXXXXX";

print_memory(a, sizeof(a));

scanf("%3c", a);

print_memory(a, sizeof(a));

return 0;

}

0xbfffe4a7:00:

0xbfffe4a6:58: X

0xbfffe4a5:58: X

0xbfffe4a4:58: X

0xbfffe4a3:58: X

0xbfffe4a2:58: X

0xbfffe4a1:58: X

0xbfffe4a0:58: X

abcde

0xbfffe4a7:00:

0xbfffe4a6:58: X

0xbfffe4a5:58: X

0xbfffe4a4:58: X

0xbfffe4a3:58: X

0xbfffe4a2:63: c

0xbfffe4a1:62: b

0xbfffe4a0:61: a

----------

#include

typedef unsigned char BYTE;

void print_memory(BYTE *start, int size)

{

int i;

for(i = size - 1; i >= 0; --i)

{

printf("%p:%02x: %c\n",

start + i,

*(start + i),

*(start + i));

}

int main(void)

{

char a[] = "XXXXXXX";

print_memory(a, sizeof(a));

scanf("%3c%2c", a, a + 1);

print_memory(a, sizeof(a));

return 0;

}

0xbffff7a7:00:

0xbffff7a6:58: X

0xbffff7a5:58: X

0xbffff7a4:58: X

0xbffff7a3:58: X

0xbffff7a2:58: X

0xbffff7a1:58: X

0xbffff7a0:58: X

abcde

0xbffff7a7:00:

0xbffff7a6:58: X

0xbffff7a5:58: X

0xbffff7a4:58: X

0xbffff7a3:58: X

0xbffff7a2:65: e

0xbffff7a1:64: d

0xbffff7a0:61: a

----------

#include

typedef unsigned char BYTE;

void print_memory(BYTE *start, int size)

{

int i;

for(i = size - 1; i >= 0; --i)

{

printf("%p:%02x: %c\n",

start + i,

*(start + i),

*(start + i));

}

int main(void)

{

char ch1 = 'X', ch2 = 'Y';

print_memory(&ch2, 4);

scanf("%3c%2c", &ch1, &ch2);

print_memory(&ch2, 4);

return 0;

}

0xbfffe629:e6: æ

0xbfffe628:48: H

0xbfffe627:58: X

0xbfffe626:59: Y

abcde

0xbfffe629:63: c

0xbfffe628:62: b

0xbfffe627:65: e

0xbfffe626:64: d