Converting string array characters to numbers

Assuming that your compiler uses an ASCII encoding then you can use the following simple arithmetic to get your answer:

1 + (strA[i] - 'a') % 9

You really don't want to implement this with a long list of if statements or indeed a switch statement.

Naturally you will have input validation issues if you have non alphabetical characters, numeric characters, upper-case characters and so on. I presume you can simply ignore those for a learning exercise.

To correct your original approach, you need to do two things:

• Use single quotes around character constants;
• Use == to check for equality;
• Terminate statements with ;.

... so your snippet becomes:

if (strA[0] == 'a')
    strB[0] = '1';
if (strA[0] == 'b')
    strB[0] = '2';
if (strA[0] == 'c')
    strB[0] = '3';

You can type the following exactly into a gwbasic editor and it will solve your problem

10 INPUT A$

12 L = LEN(A$)

15 FOR T = 1 TO L

20 M$ = MID$(A$,T,1)

25 GOSUB 70

30 B$ = B$ + V$

35 NEXT T

40 PRINT B$

50 END

55 REM -----------------

70 REM - Subroutine to convert m$ into v$

72 X = ASC(M$) : REM this is the ascii value of m$ (eg. "a" = 97)

74 X = X - 96 : REM so that 97 becomes "1"

80 IF X > 9 THEN X = X - 9 : GOTO 80

90 V$ = STR$(X) : REM just converting to a string type variable

95 RETURN : REM takes you back to line 30 where this value is added to the

96 REM final resulting B$ - when I say added I mean a char added to a string

97 REM such that   "APPL" + "E" = "APPLE"

98 REM ------------------------------------------ DONE

For ASCII, it would go somewhat like:

... make sure strB has enough space ...
for (i = 0; i < ... length of strA ... ; i++) {
    /* you should always check your input is valid */
    if (strA[i] >= 'a' && strB[i] <= 'z')
        strB[i] = (strA[i] - 'a') % 9 + 1;
    else
        strB[i] = ... some default value ...
}

For EBCDIC:

for (i = 0; i < ... length of strA ... ; i++) {
    /* you should always check your input is valid */
    if (strA[i] >= 'a' && strB[i] <= 'r')
        strB[i] = strA[i] & 0xF;
    else if (strA[i] >= 's' && strB <= 'z')
        strB[i] = (strA[i] & 0xF) - 1;
    else
        strB[i] = ... some default value ...
}

Have a closer look at an ASCII table. You'll see that all letters are encoded with some integer value. As a start, if you only have lower case letters, it's enough to substract the character code of 'a' from any letter to get what you want

int nr = strA[0] - 'a' + 1;
//now you'd need to convert back to a string; better: strB should be an array of integer

Also, = is the assignment operator; you need to use == to check for equality.

try this :)

int strB[MAX_LEN] = {0};
char *strA = malloc (MAX_LEN * sizeof(char));
int i,c = 0,x;

scanf("%s",strA);

for(i = 0 ; i<strlen(strA) ; i++){
    x = strA[i] - 'a' + 1;
    if(x >= 1 && x <= 9)
        strB[c] = x;
    else if(x <= 18){
        strB[c] = x - 10;
    else if(x <= 26){
        strB[c] = x - 19;
    if(x <= 26)
        c++;
}

or you can use ninjalj approach in the for loop, if you aleady checked the input:

for(i=0 ; i<strlen(strA) ; i++){
    strB[i] = (strA[i] - 'a') % 9 + 1;
}

or this :

for(i=0 ; i<strlen(strA) ; i++){
    if(strA[i] >= 'a' && strA[i] <= 'z'){
        strB[c] = (strA[i] - 'a') % 9 + 1;
        c++;
    }
}