C/C++计算字符串最后一个单词的长度

代码1

#include <iostream>
#include <cstring>
using namespace std;
// int str_length(char *s);
int main()
{
char str[5000];
cin.getline(str,4000);
int length,temp=0;
char *p1,*p2;
length=strlen(str);
p1=str;
while(p1!=NULL&&(p1-str)<length)
{
if(*p1==str[0])
{
p2=p1;
while(*p2!=' '&&(p1-str)<length)
{
temp++;
p2++;
p1++;
}
}
if(*p1==' ')
{
temp=0;
p1++;
p2=p1;
while(*p2!=' '&&(p1-str)<length)
{
temp++;
p2++;
p1++;
}
}
}
cout<<temp;
}

代码2

#include <iostream>
#include <cstring>
using namespace std;
int str_length(char *s);
void main()
{
char str[130];
int num, leng, i;
cin.getline(str, 129);
leng = strlen(str);
//cout<<leng<<endl;
for (i = 0; i<leng; i++)
{
if ((str[i] <= 'z'&&str[i] >= 'a') || (str[i] <= 'Z'&&str[i] >= 'A') || str[i] == ' ')
str[i] = str[i];
else
str[i] = ' ';
}

num = str_length(str);
cout << num << endl;
while (1);
}

int str_length(char *s)
{
char *ptr1, *ptr2;
int num = 0, temp, leng = strlen(s);
if (s == NULL)
{
return 0;
}
else
{
ptr1 = s;
ptr2 = NULL;
while (ptr1 != NULL && (ptr1 - s)<leng)  //若ptr1跑出s，则prt1-s大于等于leng
{
temp = 0;
if (*ptr1 != ' ')
{
ptr2 = ptr1;
while ((*ptr2) != ' ' && (ptr2 - s)<leng)
{
temp++;
ptr2++;
}
ptr1 = ptr2;
}

8f37
num = temp;
ptr1++;
}
return num;
}
}

代码3

#include<iostream>
#include<cstring>
using namespace std;
int main()
{
char a[100];
int n,i,count=0;
cin.getline(a, 100);
n = strlen(a);
i = n - 1;
while (a[i] != ' '&&i != 0)
{
count++;
i--;
}
cout << count;

}