一波C语言字符数组实用技巧集锦

#include <stdio.h>  void daoxu(char str[]){    int i;    char temp;    for(i = 0; i < strlen(str) / 2 ; i ++){      temp = str[i];      str[i] = str[strlen(str) - i-1];      str[strlen(str) - i-1] = temp;    }  } 

 int wordCount(char str[]){    int i;    int count = 0;    int word = 0;    for (i = 0 ; str[i] != '/0' ; i ++)    {      if (str[i] == ' ')      {        word = 0;      }else if (word == 0)      {        word = 1;        count ++;      }    }    return count;  } 

 void mylwr(char str[]){    int i;    for (i = 0 ; str[i] != '/0' ; i ++)    {      if (str[i] >= 'A' && str[i] <= 'Z')      {        str[i] += 'a' - 'A';      }    }  } 

 void myupr(char str[]){    int i;    for (i = 0 ; str[i] != '/0' ; i ++)    {      if (str[i] >= 'a' && str[i] <= 'z')      {        str[i] -= 'a' - 'A';      }    }  } 

 int mylen(char str[]){    int len;    for (len = 0 ; str[len] != '/0' ; len ++);    return len;  } 

 void mycat(char str1[],char str2[]){    int i,j;    for (i = 0 ; str1[i] != '/0' ;i++);    for (j = 0 ; str2[j] != '/0' ; j ++)    {      str1[i + j] = str2[j];    }    str1[i + j] = '/0';  } 

void myncat(char str1[],char str2[], int len){    int i,j;    for(i = 0; str1[i] != '/0'; i++);    for (j = 0; j < len; j++)    {      str1[i + j] = str2[j];    }    str1[i + j] = '/0';  } 

 void mycpy(char dst[],char src[]){    int i = 0;    do     {      dst[i] = src[i];    } while (src[i++] != '/0');  } 

 void myncpy(char dst[],char src[], int len){    int i;    for (i = 0; i < len; i++)    {      dst[i] = src[i];    }    dst[i] = '/0';  } 

 void longest(char dst[],char src[]){    int i = 0,j;    int count =0;    int max = -1;    do     {      if (src[i] ==' ' || src[i] == '/0')      {        if (count > max)        {          max = count;          for (j = 0; j < count; j++)          {            dst[j] = src[i - count + j];          }          dst[j] = '/0';        }        count = 0;      }else{        count++;      }    } while (src[i++] != '/0');  } 

#include <stdio.h>  int getint(char str[], int a[]){//从字符串中提取数字并放在数组中   int i = 0;   int w = 0;   int c = 0;   int j, k;   do    {     if (str[i] > '0' && str[i] <= '9')     {       w++;     }else if (w)     {       j = 0;       for (k = w; k > 0; k--)       {         j *= 10;         j += str[i - k] - '0';       }       w = 0;       a[c] = j;       c++;     }   } while (str[i++] != '/0');   return c; }  void main(){   char str[100];   int a[100];   int i, j;   gets(str);   i = getint(str,a);   for (j = 0; j < i; j++)   {     printf("%d ",a[j]);   } } 

#include <stdio.h> #include <stdlib.h>  int sumof1(int x)//求一个数转换成二进制以后1的个数 {   int countx = 0;   while(x)   {     countx ++;     x &= x-1; //每位与一次x - 1；就能消掉最后一个1   }   return countx; }  void main(){    char c[10];   int i = 999;    itoa(i, c, 10);//以10进制转换成字符数组   puts(c);    itoa(i, c, 16);//以16进制转换成字符数组   printf("0x%s/n", c);    itoa(i, c, 8);//以8进制转换成字符数组   printf("0%s/n", c);    itoa(i, c, 2);//以2进制转换成字符数组   puts(c);    i = atoi(c);//再将字符串转成整形   printf("%d/n", i);    printf("%d/n", sumof1(i));//以2进制表示时1的个数 }