明解C语言（入门篇）第十一章_明解c语言入门篇练习11-1思考

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

#include <stdio.h>
 
 
int main(void)
{
	int i, j;
	char a[][5] = { "ABCD","E","EGH" };
	char *p[] = { "PAUL","X","MAC" };
 
	i = sizeof(a) / sizeof(a[0]);
	j = sizeof(p) / sizeof(p[0]);
 
	printf("a中字符串个数为%d\n", i);
	printf("b中字符串个数为%d\n", j);
 
	return 0;
 
}

 

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:");
	scanf_s("%s", tmp, 32);
 
	puts("复制后。");
	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 len = 0;
	for (len = 0; len < strlen(s); len++)
		printf("%c", s[len]);
}
 
 
int main(void)
{
	char str[128] ;
	printf("请输入字符串:");
	scanf_s("%s", str, 32);
 
	printf("str=\"");
	put_string(str);
	puts("\"");
	return 0;
}

练习11-5

#include <stdio.h>
#include <string.h>
 
int str_chnum(const char *s, int c)
{
	int len, num = 0;
 
	for (len = 0; len < strlen(s); len++) {
		if (*(s + len) == 'c')
			num++;
	}
	return num;
}
 
int main(void)
{
	char str[128];
	char c = 'c';
 
	printf("请输入字符串：");
	scanf_s("%s", str, 32);
 
	printf("字符串中有%d个c。\n", str_chnum(str, c));
	return 0;
}

练习11-6

#include <stdio.h>
#include <string.h>
 
char* str_chr( char *s, int c)
{
	char *t = s;
	while (*s) {
		if (*s == c) {
			t = s;
			break;
		}
		else t = NULL;
		s++;
	}
	return t;
}
 
 
int main(void)
{
	char str[128];
	int c = 'c';
 
	printf("请输入字符串：");
	scanf_s("%s", str, 32);
 
	printf("目标地址为%p\n", str_chr(str, c));
 
	return 0;
}

 

练习11-7

#include <stdio.h>
#include <ctype.h>
 
void str_toupper(char *s)
{
	while (*s) {
		*s = toupper(*s);
		*s++;
	}
}
 
void str_tolower(char *s)
{
	while (*s) {
		*s = tolower(*s);
		*s++;
	}
}
 
int main(void)
{
	char s[128];
	printf("请输入字符串：");
	scanf("%s", s,32);
 
	str_toupper(s);
	printf("将字符串中的字母改为大写:%s\n", s);
	str_tolower(s);
	printf("将字符串中的字母改为小写:%s\n", s);
	return 0;
}

练习11-8

#include <stdio.h>
 
void del_digit(char *str)
{
	while (*str) {
		if ((*str >= 'a'&&*str <= 'z') || (*str >= 'A'&&*str <= 'Z')) {
			printf("%c", *str);
		}
		str++;
	}
}
 
int main(void)
{
	char str[128]="12AbC123DeF";
 
	printf("去掉数字后，字符串变为:");
	del_digit(str);
 
	return 0;
}