求解一道题。。。

[zhizinianhua]

编写函数fun，其功能是：在字符串中所有数字字符前加一个“*”字符，要求通过指针实现.


希望不要用链表之类的

[mengmingtao]

#include <cstring>
#include <iostream>
using namespace std;

char *fun(char* s){
    int i,j;
    int len = strlen(s);
    for(i=0;i<len;i++){
        if((*(s+i))>='0'&& (*(s+i))<='9'){
            for(j=len;j>i;j--){
                *(s+j+1) = *(s+j);
            }
            *(s+j+1) = *(s+j);
            *(s+i) = '*';
            i++;
            len++;
        }
    }
    return s;
}

int main(){
    char str[100] = "1234565";
    fun(str);
    cout << str <<endl;
}

[we_sky2008]

#include<stdio.h>
#include<stdlib.h>

char *func(char *str)
{
    int mum_cnt = 0;
    char *right, *left;

    if (NULL == str)
        return NULL;

    for (right = str; *right != '\0'; ++right)
    {
        if ('0' <= *right && *right <= '9')
        {
            ++mum_cnt;
        }
    }

    left = right;
    right += mum_cnt;
    *right-- = 0;

    while (left >= str)
    {
        *right-- = *--left;
        if ('0' <= *left && *left <= '9')
        {
            *right-- = '*';
        }
    }

    return str;
}

int main()
{
    char src[100] = "654321a1b2c3d4e5f6g123456";

    printf("%s\n", func(src));

    system("pause");
    return 0;
}

[we_sky2008]

[Quote=引用 2 楼 we_sky2008 的回复:]
C/C++ code


#include<stdio.h>
#include<stdlib.h>

char *func(char *str)
{
int mum_cnt = 0;
char *right, *left;

if (NULL == str)
return NULL;

for (right = str; ……
[/Quote]
while (left >= str) 改为while (left > str)

#include<stdio.h>
#include<stdlib.h>

char *func(char *str)
{
    int mum_cnt = 0;
    char *right, *left;

    if (NULL == str)
        return NULL;

    //先计算共有多少个数字字符
    for (right = str; *right != '\0'; ++right)
    {
        if ('0' <= *right && *right <= '9')
        {
            ++mum_cnt;
        }
    }

    left = right;
    right += mum_cnt;
    *right-- = 0;

    //从后往前拷贝
    while (left > str)
    {
        *right-- = *--left;
        if ('0' <= *left && *left <= '9')
        {
            *right-- = '*';
        }
    }

    return str;
}

int main()
{
    char src[100] = "654321a1b2c3d4e5f6g123456";

    printf("%s\n", func(src));

    system("pause");
    return 0;
}

[_了凡_]

每个数字前面都加*，那字符串长度就会增加，若字符串都是由数字构成的，那长度
就会增加一倍，下面这个是分配内存的版本：

#include <stdio.h>
#include <stdlib.h>

char *foo(char *str);

int main(int argc, char **argv)
{
	char *str = "a1b2c3d4e5f6";
	char *ret_str = foo(str);

	printf("ret_str = %s\n", ret_str);
	// Do NOT forget to free the allocated memory.
	free(ret_str);
	return 0;
}

char *foo(char *str)
{
	char *p = NULL, *q = NULL,
		 *tmp_str = NULL;
	int digit_count = 0;

	if (NULL == str) {
		return NULL;
	}

	for (p = str; *p != '\0'; ++p) {
		if (*p >= '0' && *p <= '9') {
			++digit_count;
		}
	}

	tmp_str = (char *) malloc(sizeof(char) * (p - str + digit_count + 1));
	if (NULL == tmp_str) {
		fprintf(stderr, "Allocate mem for tmp_str failed.");
		return NULL;
	}

	for (p = str, q = tmp_str; *p != '\0'; ++p, ++q) {
		if (*p >= '0' && *p <= '9') {
			*q++ = '*';
		}
		*q = *p;
	}
	*q = '\0';
	return tmp_str;
}

Output:
ret_str = a*1b*2c*3d*4e*5f*6

[OnMyWay2010]

[Quote=引用 3 楼 we_sky2008 的回复:]
引用 2 楼 we_sky2008 的回复:
C/C++ code


#include<stdio.h>
#include<stdlib.h>

char *func(char *str)
{
int mum_cnt = 0;
char *right, *left;

if (NULL == str)
return NULL;

for (right = str; ……
[/Quote]
恩，这种方法效率比较高

[sinanxyj]

#include <cstring>
#include <iostream>
using namespace std;

char *fun(char* s){
int i,j;
int len = strlen(s);
for(i=0;i<len;i++){
if((*(s+i))>='0'&& (*(s+i))<='9'){
for(j=len;j>i;j--){
*(s+j+1) = *(s+j);
}
*(s+j+1) = *(s+j);
*(s+i) = '*';
i++;
len++;
}
}
return s;
}

int main(){
char str[100] = "12345623345";
fun(str);
cout << str <<endl;
return 0;
}