How to reformat code to output properly? - c

Question

I have code that looks like this:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char **argv) {
int x;
if (argc != 2) {
printf("error\n");
return -1;
}
char *ptr = argv[1];
int count[256] = {0};
while (*ptr) {
if(!isdigit(*ptr)){
count[(unsigned char)*ptr]++;
ptr++;
}
else{
printf("error\n");
return -1;
}
}
int i;
int compCount = 0;
for (i = 0 ; i != 256 ; i++) {
if (count[i]) {
// compCount += printf("%c%d",i,count[i]);
compCount +=2;
}
}
int j;
if(compCount > strlen(argv[1])){
printf("%s\n", argv[1]);
}else{
for(j=0; j!=256;j++){
if(count[j]){
printf("%c%d",j,count[j]);
}
}
}
}
I am trying to work through some test cases that I was provided. For example, my code breaks at this test case:
INPUT: ./program aabccccccggeeecccccd
EXPECTED: a2b1c6g2e3c5d1
OUTPUT: a2b1c11d1e3g2
Any suggestions as to how I can fix this?

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// dst needs to at least strlen(src)*2+1 in size.
void encode(char* dst, const char* src) {
while (1) {
char ch = *src;
if (!ch) {
*dst = 0;
return;
}
size_t count = 1;
while (*(++src) == ch)
++count;
*(dst++) = ch;
dst += sprintf(dst, "%zu", count);
}
}
int main(int argc, char** argv) {
if (argc != 2) {
fprintf(stderr, "usage\n");
return 1;
}
const char* src = argv[1];
char* dst = malloc(strlen(src)*2+1);
encode(dst, src);
printf("%s\n", dst);
free(dst);
return 0;
}
$ gcc -Wall -Wextra -pedantic -std=c99 -o a a.c
$ ./a aabccccccggeeecccccd
a2b1c6g2e3c5d1
$ ./a abc
a1b1c1

Answer 2

The code does not even compile, because it had 2 errors. The main one was that the esdigit function was defined but the liberia that mentions this procedure, which is ctype (#include <ctype.h>), was not included.
Another error was that a variable x was declared but not used
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
int main(int argc, char **argv) {
if (argc != 2) {
fprintf(stderr, "error\n");
return 1;
}
char *ptr = argv[1];
int count[256] = {0};
while (*ptr) {
if(!isdigit(*ptr)){
count[(unsigned char)*ptr]++;
ptr++;
}
else{
printf("error\n");
return -1;
}
}
int i;
size_t compCount = 0;
for (i = 0 ; i != 256 ; i++) {
if (count[i]) {
compCount +=2;
}
}
int j;
if(compCount > strlen(argv[1])){
printf("%s\n", argv[1]);
}else{
for(j=0; j!=256;j++){
if(count[j]){
printf("%c%d",j,count[j]);
}
}
}
printf("\n");
return 0;
}