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] != '\0'){
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\n",str);

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

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

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

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

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

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

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

return 0;
}

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

str1 = Wearehappy.
str1 = Wearehappy.

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

str3 =
str3 =