Remove spaces from an array in C?

Question

I am trying to remove the spaces from my array "secuencia", the users give me this entry:

"1 2 3 4 5 6 7 8 9"

I want to remove the spaces, and save it in another array for later. Then, convert to integer with "ATOI" like I do with the arrays "palancas" and "palancaroja". Those two arrays only contained one number, so I had no problem with them.

please help me... I am programming in ANSI C.

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

int main(int argc, const char * argv[])
{
    char palancas [20000];
    int palancai;
    char palancaroja[10];
    int palancarojai;
    char secuencia[20000];
    char temp[20000];
    int j = 0;

    printf("Dame El Numero De Palancas:");
    fgets(palancas, 20000, stdin);

    printf("Dame La Posision De La Palanca Roja:");
    fgets(palancaroja, 10, stdin);

    palancai = atoi(palancas);
    palancarojai = atoi(palancaroja);

    printf("Dame La cadena");
    fgets(secuencia, 20000, stdin);

    for (int i = 0; i < palancai; i++) {

        if (secuencia [i] != ' ') {

        temp [i] = secuencia [i];


            printf("%s", temp);


        }
    }
}

Answer 1

This is the simplest way to remove spaces from a string.

char *SourcePtr = secuencia;
char *TargetPtr = SourcePtr;

while (*SourcePtr != 0)
{
    if (*SourcePtr != ' ')
    {
       *TargetPtr = *SourcePtr;
       TargetPtr += 1;
    }
    SourcePtr += 1;
}
*TargetPtr = 0;

Answer 2

Translated version of critical section

for (int i = 0; i < length; i++) {
    if (source[i] != ' ') {
        temp[i] = source[i];
        printf("%s", temp);
    }
}

This code copies every character from the array source to the array temp , but simply skips spaces. So if temp is initialized with XXXXX and source is ABC , then temp is AXBXC after the execution of the loop.

You have use two indexes (see other answer)

Answer 3

#include <stdio.h>

//copy to d from s removed space
void remove_space(char *d, const char *s){
    for(;*s;++s){
        if(*s != ' ')
            *d++ = *s;
    }
    *d = *s;
}

int main(){//DEMO
    char secuencia[] = "1 2 3 4 5 6 7 8 9";
    char temp[sizeof(secuencia)];
    remove_space(temp, secuencia);
    puts(temp);//123456789
    return 0;
}

Answer 4

You could use strtok and tokenize the string that you get with the delimiter string being " ".

In other words:

char * tok;
int i = 0;
tok = strtok(secuencia, " ");
while(tok != NULL){
    temp[i] = tok[0];
    i++;
    tok = strtok(NULL, " ");
}

This would only work if it's guaranteed that it's a single digit between each space though. Another way to copy it would be to use another loop, cycling through strtok until '\\0' is reached, or using strcpy.

Answer 5

first I think that your for loop is looking at the wrong variable. you are trying to loop on palancai where really you want to loop on secuencia.

Below you can find a function that will parse your int.

int MyIntParse(char* str)
{
    int iReturn = 0;
    for(int i=0;i<20000;++i)
    {
        iReturn *=10;
        switch(str[i])
        {
            case '0':
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7':
            case '8':
            case '9':
            case '0':
                iReturn = iReturn + (str[i] - '0');
                break;
        }
    }
    return iReturn;
}