void ReplaceBlank(char str[], int maxLength) {if(str == NULL || maxLength <=0)return;//calculate the new length after replacing and number of Blanksint originalLength = 0;int numberOfBlank = 0;int index = 0;for(index = 0; str[index] != '\0'; index++) {if(str[index] == ' ')++numberOfBlank;}originalLength = index+1;//if the number of blank is 0, nothing changesif(numberOfBlank==0)return;//if the new length exceeds the max lengthint newLength = originalLength+2*numberOfBlank;if (newLength > maxLength) {cout << "new Length exceeds the max Length!" << endl;return;}//start at the character before '\0'int indexOfOriginal = originalLength-2;int indexOfNew = newLength-2;while (indexOfOriginal>=0 && indexOfNew > indexOfOriginal) {if (str[indexOfOriginal] == ' ') {str[indexOfNew--] = '0';str[indexOfNew--] = '2';str[indexOfNew--] = '%';} else {str[indexOfNew--] = str[indexOfOriginal];}--indexOfOriginal;}//add a '\0' at laststr[newLength-1] = '\0';
}

#include <iostream>
#include <stdio.h>
using namespace std;void ReplaceBlank(char str[], int maxLength) {if(str == NULL || maxLength <=0)return;//calculate the new length after replacing and number of Blanksint originalLength = 0;int numberOfBlank = 0;int index = 0;for(index = 0; str[index] != '\0'; index++) {if(str[index] == ' ')++numberOfBlank;}originalLength = index+1;//if the number of blank is 0, nothing changesif(numberOfBlank==0)return;//if the new length exceeds the max lengthint newLength = originalLength+2*numberOfBlank;if (newLength > maxLength) {cout << "new Length exceeds the max Length!" << endl;return;}//start at the character before '\0'int indexOfOriginal = originalLength-2;int indexOfNew = newLength-2;while (indexOfOriginal>=0 && indexOfNew > indexOfOriginal) {if (str[indexOfOriginal] == ' ') {str[indexOfNew--] = '0';str[indexOfNew--] = '2';str[indexOfNew--] = '%';} else {str[indexOfNew--] = str[indexOfOriginal];}--indexOfOriginal;}//add a '\0' at laststr[newLength-1] = '\0';
}void test(char str[], int maxLength) {cout << "-----------test-------------" << endl;printf("Original: %s\n", str);ReplaceBlank(str, maxLength);printf("Replaced: %s\n", str);cout << "-----------end---------------" << endl;}
int main() {/*char str[50] = "hello world and s";ReplaceBlank(str, 50);printf("%s\n", str);*/char str1[50]="hello world and s";char str2[50]="";char str3[20]="hello world! fdsjkd";char str4[50]="    helloweroddfsd";char str5[50]="       ";test(str1, 50);test(str2, 50);test (NULL, 50);test(str3, 20);test(str4, 50);test(str5, 50);return 0;
}