字符串面试题.doc

1. 写一个将整数转换成字符串的函数itoa解析：整数转化成字符串，可以采用加0,然后再逆序，整数加0就会隐形转化为char类型的数。#include #include using namespace std;int main(void)int num = 12345, j=0, i=0;char temp7, str7;while(num)tempi = num%10 + 0;i+;num = num/10;tempi = 0;printf(temp = %sn,temp);i=i-1;while(i=0)strj = tempi;j+;i-;strj=0;printf(string = %sn, str);return 0;2. 编程实现字符串数转化成整数的方法。解析：可以采用减 0 再乘10累加的方法，字符串减 0 就会隐性转换为int类型的数#include#includeint main(void)int num=12345, j=0, i=0, sum=0;char temp7=1, 2, 3, 4, 5, 0, str7;while (tempi)sum=sum*10+(tempi-0);i+;printf(sum=%dn, sum)return 0;1)写出在母串中查找子串出现次数的代码.cpp view plaincopy1 int count1(char* str,char* s) 2 3 char* s1; 4 char* s2; 5 int count = 0; 6 while(*str!=/0) 7 8 s1 = str; 9 s2 = s; 10 while(*s2 = *s1&(*s2!=/0)&(*s1!=0) 11 12 s2+; 13 s1+; 14 15 if(*s2 = /0) 16 count+; 17 str+; 18 19 return count; 20 2）查找第一个匹配子串位置,如果返回的是s1长度len1表示没有找到cpp view plaincopy21 size_t find(char* s1,char* s2) 22 23 size_t i=0; 24 size_t len1 = strlen(s1) 25 size_t len2 = strlen(s2); 26 if(len1-len20) return len1; 27 for(;ilen1-len2;i+) 28 29 size_t m = i; 30 for(size_t j=0;jlen2;j+) 31 32 if(s1m!=s2j) 33 break; 34 m+; 35 36 if(j=len) 37 break; 38 39 return i *r) 53 return 1; 54 else if(*l = *r) 55 return 0; 56 return -1; 57 5) 实现字符串翻转cpp view plaincopy58 void reserve(char* str) 59 60 assert(str != NULL); 61 char * p1 = str; 62 char * p2 = str-1; 63 while(*+p2); /一般要求不能使用strlen 64 p2 -= 1; 65 while(p1p2) 66 67 char c = *p1; 68 *p1+ = *p2; 69 *p2- = c; 70 71 6）、用指针的方法，将字符串“ABCD1234efgh”前后对调显示/不要用strlen求字符串长度，这样就没分了代码如下: cpp view plaincopy72 char str123 = ABCD1234efgh; 73 char * p1 = str123; 74 char * p2 = str123-1; 75 while(*+p2); 76 p2 -= 1; 77 while(p1p2) 78 79 char c = *p1; 80 *p1+ = *p2; 81 *p2- = c; 82 7) 给定字符串A和B,输出A和B中的最大公共子串。比如A=aocdfe B=pmcdfa 则输出cdfcpp view plaincopy83 i nclude 84 i nclude 85 i nclude 86 char *commanstring(char shortstring, char longstring) 87 88 int i, j; 89 char *substring=malloc(256); 90 if(strstr(longstring, shortstring)!=NULL) /如果，那么返回shortstring 91 return shortstring; 92 for(i=strlen(shortstring)-1;i0; i-) /否则，开始循环计算 93 94 for(j=0; jstrlen(str2) /将短的字符串放前面 113 comman=commanstring(str2, str1); 114 else 115 comman=commanstring(str1, str2); 116 printf(the longest comman string is: %s/n, comman); 117 8) 判断一个字符串是不是回文118 int IsReverseStr(char *str) 119 120 int i,j; 121 int found=1; 122 if(str=NULL) 123 return -1; 124 char* p = str-1; 125 while(*+p!= /0); 126 -p; 127 while(*str=*p&strp) str+,p-; 128 if(str src ) /考虑覆盖情况 139 140 d = (char *)dst + len - 1; 141 s = (char *)src + len - 1; 142 while ( len = 4 ) /循环展开，提高执行效率 143 144 *d- = *s-; 145 *d- = *s-; 146 *d- = *s-; 147 *d- = *s-; 148 len -= 4; 149 150 while ( len- ) 151 152 *d- = *s-; 153 154 155 else if ( dst = 4 ) 160 161 *d+ = *s+; 162 *d+ = *s+; 163 *d+ = *s+; 164 *d+ = *s+; 165 len -= 4; 166 167 while ( len- ) 168 169 *d+ = *s+; 170 171 172 return dst; 173 出现次数相当频繁10）写一个函数,它的原形是int continumax(char *outputstr,char *intputstr)功能：在字符串中找出连续最长的数字串，并把这个串的长度返回，并把这个最长数字串付给其中一个函数参数outputstr所指内存。例如：abcd12345ed125ss123456789的首地址传给intputstr后，函数将返回9，outputstr所指的值为123456789174 int continumax(char *outputstr, char *inputstr) 175 176 char *in = inputstr, *out = outputstr, *temp, *final; 177 int count = 0, maxlen = 0; 178 while( *in != /0 ) 179 180 if( *in 47 & *in 47 & *in 58 ; in+ ) 183 count+; 184 185 else 186 in+; 187 if( maxlen count ) 188 189 maxlen = count; 190 count = 0; 191 final = temp; 192 193 194 for(int i = 0; i iCount) 216 iCount = iTemp, cpDest = cpTemp; 217 if(!*cpSource) 218 break; 219 220 +cpSource; 221 222 return cpDest; 223 排序算法:冒泡排序: 出现次数相当频繁cpp view plaincopy224 void buble(int *a,int n) 225 226 for(int i=0;in;i+) 227 228 for(int j=1;jn-i;j+) 229 230 if(ajaj-1) 231 232 int temp=aj; 233 aj = aj-1; 234 aj-1 = temp; 235 236 237 238 239 插入排序：240 void insertsort(int* a,int n) 241 242 int key; 243 for(int j=1;j=0&aikey;i-) 247 248 ai+1 = ai; 249 250 ai+1 = k