Upper Case or Lower Case String in Linux C

Published on Tuesday, September 6, 2011

There is no direct function to convert a string to upper case or lower case in Linux C. Here we collect 2 functions from internet:

#include <ctype.h>
  
static char* Str2Upper(char *str)   
{   
    if(str == NULL)    
        return NULL;    
    
    char *p = str;   
    
    while(*str)    
    {   
        *str = toupper(*str);   
        str++;   
    }    
    
    return p;   
}
  
 
  
static char* Str2Lower(char *str)    
{     
if(str == NULL)    
return NULL;    
    
char *p = str;     
    
while(*str)    
{     
*str = tolower(*str);     
str++;     
}    
    
return p;     
}