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copied!<p>You might just reuse this <a href="https://stackoverflow.com/questions/17112494/how-to-expand-environment-variables-in-ini-files-using-boost/17128601#17128601">c++ solution</a> (replacing the generic iterators by hardcoding <code>char*</code> instead).</p> <p>I gave it a whirl. However, I wish to give a warning: it looks like you're trying to implement an expression parser. I'd strongly advise you to either</p> <ul> <li>handroll a (recursive descent) parser</li> <li>use flex/bison (or lex/yacc)</li> </ul> <p>so you don't paint yourself in an awkward corner of error-prone text-handling in C.</p> <blockquote> <h3><strong>Edit:</strong> I rewrote <a href="http://pastebin.com/AgcDi7YU" rel="nofollow noreferrer">your C program</a> using C++; you can see it <a href="http://coliru.stacked-crooked.com/view?id=814ec79f83fa4d93a9be9f5500988b50-0681a6d6fa3348403a2b0d4989bfddf5" rel="nofollow noreferrer">working live here</a>.</h3> <h3><strong>Edit 2:</strong> Another fixup of your C program in pure C: <strong><a href="http://ideone.com/ExnufJ" rel="nofollow noreferrer">http://ideone.com/ExnufJ</a></strong> <em>updated to support iterative expansions now, too</em></h3> </blockquote> <p>The answer just concerns itself with the pure C approach:</p> <p>So, let's get started. I assumed a sample "spreadsheet" (it could contain numbers instead of strings):</p> <pre><code>const char* cells[][4] = { /* A B C D */ { "the" , "lazy" , "cow" , "jumped" }, /* 1 */ { "over" , "the" , "quick", "brown" }, /* 2 */ { "paper", "packages", "tied" , "up" }, /* 3 */ { "with" , "silver" , "white", "winters" }, /* 4 */ { "that" , "melt" , "fox" , "springs" }, /* 5 */ }; </code></pre> <p>Using just two helpers:</p> <pre><code>const char* get_cell_value(const char* coordinate_b, const char* coordinate_e); char* expand_cell_references(const char* f, const char* const l, char* o); /*the magic engine*/ </code></pre> <p>we can write the following demo program:</p> <pre><code>int main() { const char in[] = "The C2 D2 C5 D1 A2 B2 B1 dog!"; char out[1024] = {0}; expand_cell_references(in, in+strlen(in), out); puts(out); /* "The quick brown fox jumped over the lazy dog!" */ return 0; } </code></pre> <p>which prints the well-known test phrase as per the comment. Now, <code>get_cell_value</code> is really simple:</p> <pre><code>const char* get_cell_value(const char* coordinate_b, const char* coordinate_e) { size_t col = 0, row = 0; const char* it; for (it=coordinate_b; it != coordinate_e; ++it) { if (*it >= 'A' && *it <= 'Z') col = 26*col + (*it - 'A'); if (*it >= '0' && *it <= '9') row = 10*row + (*it - '0'); /* or use atoi and friends */ } row--; /* 1-based row nums in Excel */ return cells[row][col]; /* 1-based indexes in Excel */ } </code></pre> <p>And <code>expand_cell_references</code> is slightly more involved, being a simple DFA parser:</p> <pre><code>char* expand_cell_references(const char* f, const char* const l, char* o) { enum parser_state { other, in_coord_col, in_coord_row } state = other; /*temporary storage for coordinates being parsed:*/ char accum[16] = {0}; char* accit = accum; while (f!=l) { switch(state) /*dummy, the transitions flow in fallthrough order for now*/ { case other: *(accit = accum) = 0; /*reset the accumulator*/ while (f!=l && !(*f>='A' && *f<='Z')) *o++ = *f++; /*fallthrough*/ case in_coord_col: while (f!=l && *f>='A' && *f<='Z') *accit++ = *f++; /*fallthrough*/ case in_coord_row: { const char* expanded = accum; if (f!=l && *f>='0' && *f<='9') { while (f!=l && *f>='0' && *f<='9') *accit++ = *f++; expanded = get_cell_value(accum, accit); } else { *accit = 0; } while (*expanded) *o++ = *expanded++; continue; /*state = other;*/ } } } return o; } </code></pre> <p>I took some shortcuts there, because this grammar is so minimalist, but it should give you a proper idea of where to start.</p> <blockquote> <p>See a live demo here <strong><a href="http://ideone.com/kS7XqB" rel="nofollow noreferrer">http://ideone.com/kS7XqB</a></strong> so you can play with it yourself. Note that I added debugging (asserts) to the <code>get_cell_value</code> function so you don't accidentally reference out-of-bounds indexes.</p> </blockquote>

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