明解C语言入门篇练习题第十一章

练习11-1

#include <stdio.h>

int main(void)
{
	char *p = "123";

	printf("p = \"%s\"\n", p);

	p = "456"+1;

	printf("p = \"%s\"\n", p);

	return 0;
}

练习11-2 补

练习11-3

#include <stdio.h>

char *str_copy(char *d, const char *s)
{
	char *t = d;

	while (*d++ = *s++)
		;
	return t;
}

int main(void)
{
	char str[128] = "ABC";
	char tmp[128];

	printf("str = \"%s\"\n", str);

	printf("复制的是：", tmp);
	scanf("%s", tmp);

	

	puts("复制了。");
	printf("str = \"%s\"\n", str_copy(str, tmp));

	return 0;
}

练习11-4

#include <stdio.h>
#include<string.h>

void put_string(const char *s)
{
	int str_len;
	int i;
	str_len = strlen(s);
	for (i = 0; i < str_len; i++)
	{
		printf("%c",*s);
		s++;
	}
	return;
}

int main(void)
{
	char s[] = "abcdef";
	put_string(s);
	printf("\n");

	return 0;
}

练习11-5

#include <stdio.h>
#include<string.h>

int str_chnum(const char *s,int c)
{
	int num = 0;
	while (*s != '\0')
	{
		if (*s == c)
			num++;
		s++;
	}

	return num;
}

int main(void)
{
	char s[128];
	char c;
	printf("input string s:");
	scanf("%s",s);
	getchar();//clear buffer
	printf("input character:");
	scanf("%c",&c);
	printf("string %s has %d character %c\n",s,str_chnum(s,c),c);
	
	return 0;
}

练习11-6

#include <stdio.h>
#include<string.h>

char *str_chr(const char *s,int c)
{
	int *chr_flag;
	while (*s != '\0')
	{
		if (*s == c)
		{
			chr_flag = s;
			break;
		}
		else
			chr_flag = NULL;
		s++;
	}
	return chr_flag;
}

int main(void)
{
	char s[128];
	char c;
	printf("input string s:");
	scanf("%s",s);
	getchar();//clear buffer
	printf("input character:");
	scanf("%c",&c);
	printf("pointer of character %c is %p\n",c,str_chr(s,c));
	
	return 0;
}

练习11-7

#include <stdio.h>  
#include <ctype.h>
      
void str_toupper(char *s)
{
	while(*s!='\0')
	{
		*s = toupper(*s);
		s++;
	}
	return;
}

void str_tolower(char *s)
{
	while(*s!='\0')
	{
		*s = tolower(*s);
		s++;
	}
	return;
}

int main(void)  
{  
	int i;
	char s[128];
	printf("input string s:");
	scanf("%s",s);

	printf("output upper string:");
	str_toupper(s);
	printf("%s",s);
	printf("\n");

	printf("output lower string:");
	str_tolower(s);
	printf("%s",s);
	printf("\n");

    return 0;
}  

练习11-8 暂时有误

练习11-9 先不写

练习11-10 先不写

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