从头学习C语言之字符串处理函数

     #include<stdio.h>
     #include<string.h>
     int main()
     {
       char str[]="i love fishc.com!";
         printf("sozeof(str)= %d\n",sizeof(str));
         printf("strlen(str)= %u\n",strlen(str));
                                                                                  
   return 0;
    }

   #include<stdio.h>
   #include<string.h>
   int main()
   {
    char str1[]="original string";
     char str2[]="new string";
     char str3[100];
   
     strcpy(str1,str2); 10   strcpy(str3,"copy sucessful");                                               
  
    printf("str1:%s\n",str1);                            
    printf("str2:%s\n",str2);
    printf("str3:%s\n",str3);
                           
                             
                         
    return 0;            
 } 

   #include<stdio.h>
   #include<string.h>
   int main()
   {
   char str1[]="to be or not to be";
     char str2[40];
   
    strncpy(str2,str1,5);
     str2[5]='\0';  //在结尾加上'\0'                                                              
                                     
    printf("str2:%s\n",str2);         
                                      
    return 0;                         
  }

   #include<stdio.h>
   #include<string.h>
   int main()
   {
    char str1[]="to be or not to be";
    char str2[]="fishc.com!";
  
     strcat(str1," ");//在str1后面加上个空格，没什么作用，仅仅为了好看点          
     strcat(str1,str2);
  
    printf("str1:%s\n",str1);
 
    return 0;
  }

   #include<stdio.h>
  #include<string.h>
  int main()
   {
     char str1[]="to be or not to be";
    char str2[]="fishc.com!";
   
     strncat(str1," ",2);//2用来限定所加的字符个数
     strncat(str1,str2,5);
    //不需要加'\0'来表示结束,这个会自己加                                        
    printf("str1:%s\n",str1);
 
   return 0;
  }

   #include<stdio.h>
   #include<string.h>
   int main()
   {
     char str1[]="fishc.com!";
     char str2[]="fishc.com!";
        if(!strcmp(str1,str2))//strcmp前面要加'非'(!),因为strcmp判断相等的话返回值为0
     {
      printf("两个字符串完全一致！\n");
    }
    else
    {
      printf("两个字符串存在差异！\n");
    }
  
    return 0;
  }

   #include<stdio.h>
   #include<string.h>
   int main()
   {
     char str1[]="fishc.cfm!";
    char str2[]="fishc.com!";
   
     if(!strncmp(str1,str2,5))//strcmp前面要加'非'(!),因为syrcmp判断一致的话返回值    为0
     {
      printf("两个字符串完全一致！\n");                                          
    }                
    else                                        
    {                  
      printf("两个字符串存在差异！\n");
    }                                     
  
  return 0;                                                        
  }