Question

How to extract uppercase characters (capital letters) from a string in C

Answer 1

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

char *extract_uppercase(char s[])  { 
   
    int len = strlen(s);
     
    char *upper_s = (char *)malloc((len * sizeof(char)) + 1);
   
    for (int i = 0, li = 0; i < len; i++) { 
        if (s[i] >= 65 && s[i] <= 90) {
            upper_s[li++] = s[i]; 
        }
    } 
       
    return upper_s;
} 	  

int main() 
{                       
    char s[] = "cCPproRO"; 
   
    char *uc = extract_uppercase(s);
	puts(uc);
	free(uc);
   
    return 0; 
} 
 
 
 
/*
run:
 
CPRO
 
*/

 

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