剑指offer 04_替换字符串中的空格

#include <stdio.h>

void ReplaceBlank(char string[],int length){
        if(string == NULL || length == 0){
                return;
        }

        int originalLength = 0;//
        int blankCount = 0;

        while(string[originalLength] != ''){
                if(string[originalLength] == ' '){
                        ++blankCount;
                }
                ++originalLength;
        }

        int newLength = originalLength + blankCount * 2;

        if(newLength > length){//not enough space
                return;
        }

        int indexFirst = originalLength;
        int indexSecond = newLength;
        while(indexFirst>=0 && indexSecond>indexFirst){
                if(string[indexFirst] == ' '){
                        string[indexSecond--] = '0';
                        string[indexSecond--] = '2';
                        string[indexSecond--] = '%';
                }else{
                        string[indexSecond--] = string[indexFirst];
                }
                --indexFirst;
        }
}


int main(){
        char str[50] = "We are happy.";
        printf("str = %s
",str);

        ReplaceBlank(str,50);
        printf("str = %s

",str);


        char str1[50] = "Wearehappy.";
        printf("str1 = %s
",str1);

        ReplaceBlank(str1,50);
        printf("str1 = %s

",str1);


        char str2[50] = "   We are happy.";
        printf("str2 = %s
",str2);

        ReplaceBlank(str2,50);
        printf("str2 = %s

",str2);


        char str3[50] = "";
        printf("str3 = %s
",str3);

        ReplaceBlank(str3,50);
        printf("str3 = %s

",str3);


        return 0;
}

结果

str = We are happy.
str = We%20are%20happy.

str1 = Wearehappy.
str1 = Wearehappy.

str2 =    We are happy.
str2 = %20%20%20We%20are%20happy.

str3 = 
str3 =